delivered the opinion of the court:
The question presented in this appeal is whether the trial court properly dismissed two counts of plaintiffs’ complaint for failure to state a cause of action. Plaintiffs, Tommie and Fannie Boyd, filed a five-count complaint in the circuit court of Cook County against defendants, Travelers Insurance Company (Travelers) and the Coleman Company, Inc. (Coleman). Counts I and II of the complaint allege negligent and willful and wanton spoliation of evidence against Travelers. Counts III and IV allege products liability and negligence claims against Coleman. Count V contains a loss of consortium claim. Travelers filed a motion to dismiss the negligent and willful and wanton spoliation counts, which the trial court granted pursuant to section 2 — 615 of the Code of Civil Procedure (735 ILCS 5/2 — 615 (West 1992)). The court found that the actions were premature because actual injury could not be alleged until plaintiffs lost the underlying suit against Coleman.
Pursuant to Supreme Court Rule 308 (134 Ill. 2d R. 308), the trial court certified the following question for interlocutory appeal:
"Whether a plaintiff in a spoliation of evidence case must plead and prove that he lost the underlying civil *191case, or whether it is sufficient that he plead a significant impairment of his ability to prove the underlying suit.”
The appellate court denied an application for leave to appeal. We granted plaintiffs’ petition for leave to appeal to this court. 145 Ill. 2d R. 315.
On February 4,1990, Tommie Boyd (Boyd) was working inside a van belonging to his employer, Superior Foods. To keep the van warm, Boyd was using a propane catalytic heater, which had been designed, manufactured, and distributed by Coleman. An explosion occurred, allegedly caused by propane gas escaping from the heater. Boyd sustained serious personal injuries and other damages. The heater was Boyd’s personal property.
Boyd filed a claim for workers’ compensation benefits against his employer and Travelers, his employer’s workers’ compensation insurer. On February 6, 1990, a Travelers claim adjuster, Tu Chi (Chi), and another Travelers employee, John Engelke, visited the Boyd residence. They took possession of the Coleman heater, telling Boyd’s wife, Fannie, that Travelers needed the heater in order to investigate her husband’s workers’ compensation claim. They also told Fannie that Travelers would inspect and test the heater to determine the cause of the explosion.
Chi transported the heater to a Travelers office and stored it in a closet. Subsequently, when Boyd asked that the heater be returned to him, Travelers was unable to locate it. On September 27, 1991, Boyd sought a court order compelling Travelers to return the heater. Travelers’ response admitted that its employees took possession of the heater and placed it in a closet, from which it later disappeared. Travelers had never tested the heater.
In counts I and II of their complaint, plaintiffs *192charge that they have been injured by Travelers’ loss of the heater because no expert could testify with certainty as to whether the heater was defective or dangerously designed. Therefore, they allege, Travelers’ loss of the heater has irrevocably prejudiced and adversely affected their products liability action against Coleman.
Travelers’ motion to dismiss counts I and II contended that negligent and intentional spoliation of evidence are not recognized torts under Illinois law. In the alternative, Travelers claimed that, even if Illinois was to recognize either cause of action, plaintiffs’ claims were premature because the underlying products liability action against Coleman was still pending. Travelers argued that, until plaintiffs lose the underlying action, they have suffered no actual injury, which is a necessary element to any cause of action. Therefore, Travelers concluded, plaintiffs must first lose the underlying suit in which the missing evidence would have been used.
The trial court granted Travelers’ motion and dismissed counts I and II without prejudice. The trial court stated that a spoliation of evidence claim would be recognized in Illinois given the right facts. However, it agreed with Travelers that plaintiffs’ claims were premature unless and until they lost the underlying suit against Coleman, thereby sustaining an actual injury. Accordingly, the trial court gave plaintiffs leave to refile counts I and II following the resolution of their products liability action against Coleman.
The question as certified by the trial court assumes that Illinois courts recognize "spoliation of evidence” as an independent cause of action. On the contrary, this court, consistent with a majority of jurisdictions, has *193never done so.1 For reasons that follow, we today hold that an action for negligent spoliation can be stated under existing negligence law.
When this court accepts an appeal involving a certified question, we may “enter any judgment and make any order that ought to have been given or made, and make any other and further orders and grant any relief *** that the case may require.” (134 Ill. 2d R. 366(a)(5).) Counts I and II, which purport to state claims for *194negligent and willful and wanton spoliation of evidence, were dismissed under section 2 — 615 for failure to state a cause of action. The question presented by a section 2 — 615 motion to dismiss is whether the plaintiff has alleged sufficient facts in the complaint which, if proved, would entitle the plaintiff to relief. (Urbaitis v. Commonwealth Edison (1991), 143 Ill. 2d 458, 475.) All well-pleaded facts in the complaint are taken as true. A motion to dismiss should be denied where a cause of action is stated, even if it is not the cause of action intended by the plaintiff. Doe v. Calumet City (1994), 161 Ill. 2d 374, 388.
Here, count I of plaintiffs’ complaint alleges that Boyd sustained serious personal injuries and other damages when the Coleman heater exploded. His wife, Fannie, relinquished the heater to two Travelers employees. The employees told her that they needed the heater to investigate Boyd’s workers’ compensation claim, and that they would inspect and test the heater to determine what caused the explosion. The heater, initially placed in a closet, later could not be found. Plaintiffs’ complaint charges that Travelers’ loss of the heater has impaired their ability to prove the products liability claim against Coleman. The legal effect of these factual allegations is to state a cause of action against Travelers for negligence.
Courts have long afforded redress for the destruction of evidence and, in our opinion, traditional remedies adequately address the problem presented in this case. An action for negligent spoliation can be stated under existing negligence law without creating a new tort. (See, e.g., Pirocchi v. Liberty Mutual Insurance Co. (E.D. Pa. 1973), 365 F. Supp. 277, 281-82 (involving a factual scenario virtually identical to the facts of the present case).) To state a cause of action for negligence, a plaintiff must plead the existence of a duty owed by the *195defendant to the plaintiff, a breach of that duty, an injury proximately caused by the breach, and damages. Estate of Johnson v. Condell Memorial Hospital (1988), 119 Ill. 2d 496, 503; Cunis v. Brennan (1974), 56 Ill. 2d 372, 374.
The general rule is that there is no duty to preserve evidence; however, a duty to preserve evidence may arise through an agreement, a contract, a statute (see Rodgers v. St. Mary’s Hospital (1992), 149 Ill. 2d 302) or another special circumstance. Moreover, a defendant may voluntarily assume a duty by affirmative conduct. (See Nelson v. Union Wire Rope Corp. (1964), 31 Ill. 2d 69, 74.) In any of the foregoing instances, a defendant owes a duty of due care to preserve evidence if a reasonable person in the defendant’s position should have foreseen that the evidence was material to a potential civil action.
In this case, count I of plaintiffs’ complaint properly pleads a duty and a breach of that duty. It alleges that, two days after Boyd’s injury, two Travelers employees visited the Boyd home, telling Fannie that they needed the heater to investigate Boyd’s workers’ compensation claim. The heater belonged to Boyd. The employees knew that the heater was evidence relevant to future litigation. Under these alleged circumstances, Travelers assumed a duty to preserve Boyd’s property. Plaintiffs’ complaint also charges that Travelers breached its assumed duty by losing the heater.
The third and fourth elements necessary to state a valid cause of action in negligence are causation and damages. According to Travelers, plaintiffs cannot properly allege these elements because they must first lose their underlying cause of action against Coleman in order to sustain an actual injury. See Federated Mutual Insurance Co. v. Litchfield Precision Components, Inc. (Minn. 1990), 456 N.W.2d 434; Petrik v. Monarch Print *196 ing Corp. (1986), 150 Ill. App. 3d 248; Fox v. Cohen (1980), 84 Ill. App. 3d 744.
Plaintiffs, on the other hand, maintain that count I of their complaint sufficiently alleges causation and damages. Moreover, they insist that they should not be required to lose the underlying lawsuit before pursuing a cause of action against Travelers. They argue that a single jury should be allowed to try both claims concurrently, thereby saving judicial time and expense, and avoiding piecemeal litigation. It would be unfair to subject them to the burden of pursuing two trials, plaintiffs argue, especially where the second trial would take place several years after the first. Lastly, they note that the jury hearing the underlying claim would be in the best position to know whether the missing evidence in actuality affected the outcome of the case. Plaintiffs maintain that a second jury could only speculate as to the reason they failed to prevail in any earlier litigation.
Initially, we note our disagreement with Travelers’ assertion that for plaintiffs to allege actual injury from the loss of the heater, they must first pursue and lose the underlying claim. To plead causation, a plaintiff must allege that an injury proximately resulted from a breach of a duty. (Moudy v. New York, Chicago, & St. Louis R.R. Co. (1944), 385 Ill. 446, 453-54.) Therefore, in a negligence action involving the loss or destruction of evidence, a plaintiff must allege sufficient facts to support a claim that the loss or destruction of the evidence caused the plaintiff to be unable to prove an underlying lawsuit.2
Here, plaintiffs’ complaint alleges that Travelers not *197only lost the heater, but failed to test it to determine the cause of the explosion. Plaintiffs were thereby deprived of the key piece of evidence in their products liability lawsuit against Coleman — the product itself. They claim that, as a result, no expert could testify without doubt whether the heater was defective or dangerously designed. These allegations are sufficient to support the theory that Travelers’ loss of the heater caused plaintiffs to be unable to prove their suit against Coleman.
Actual damages must be alleged as well. (See Jeffrey v. Chicago Transit Authority (1962), 37 Ill. App. 2d 327, 335; see generally Cunis, 56 Ill. 2d at 374.) A threat of future harm, not yet realized, is not actionable. The wrongful conduct must impinge upon a person. Consequently, a plaintiff is required to allege that a defendant’s loss or destruction of the evidence caused the plaintiff to be unable to prove an otherwise valid, underlying cause of action. A plaintiff must prove this before the harm has been realized.
In the case subjudice, plaintiffs allege sufficient facts supporting the theory that they have suffered an inability to succeed in their otherwise valid products liability action against Coleman. Plaintiffs plead that Boyd sustained serious personal injuries when the Coleman heater exploded. Through this statement and count III of their complaint, which sets forth the products liability action, plaintiffs allege facts giving *198rise to the underlying suit. As discussed above, plaintiffs’ pleadings also allege a nexus between Travelers’ loss of the heater and their inability to prove the underlying action. Accordingly, we find that count I of the complaint sufficiently alleges actual damages. We, however, express no opinion on the appropriate measure of damages. The amount of damages should be determined by the trial court and the trier of fact after a full trial on the merits. See Petrik, 150 Ill. App. 3d at 260-64.
Based on the foregoing, count I of plaintiffs’ complaint alleges facts sufficient to state a cause of action in negligence. We also agree with plaintiffs that a single trier of fact may be allowed to hear an action for negligent spoliation concurrently with the underlying suit on which it is based. (Miller v. Allstate Insurance Co. (Fla. App. 1990), 573 So. 2d 24, 28 n.7 (specifically finding that a jury trying the two claims in a single proceeding is in the best position to determine the issues); see also Smith v. Howard, Johnson Co. (1993), 67 Ohio St. 3d 28, 615 N.E.2d 1037, 1038; Smith v. Superior Court (1984), 151 Cal. App. 3d 491, 498, 198 Cal. Rptr. 829, 833-34.) A single trier of fact would be in the best position to resolve all the claims fairly and consistently. If a plaintiff loses the underlying suit, only the trier of fact who heard the case would know the real reason why. This factor is important because a spoliator may be held liable in a negligence action only if its loss or destruction of the evidence caused a plaintiff to be unable to prove the underlying suit.3
We therefore encourage plaintiffs and the trial court *199to employ joinder in this case. In Illinois, "plaintiffs may join any causes of action, against any *** defendants.” (735 ILCS 5/2 — 614(a) (West 1992).) The joinder of defendants is governed by section 2 — 405 of the Code of Civil Procedure (735 ILCS 5/2 — 405 (West 1992)). Defendants "against whom a liability is asserted either jointly, severally or in the alternative arising out of the same transaction or series of transactions” may be joined. (735 ILCS 5/2 — 405(a) (West 1992); see also 735 ILCS 5/2 — 405(c) (West 1992).) The objective of joinder is the economy of actions and trial convenience. The determining factors are that the claims arise out of closely related "transactions” and that there is in the case a significant question of law or fact that is common to the parties. City of Nokomis v. Sullivan (1958), 14 Ill. 2d 417, 420.
These requirements have been met here. The claims against Coleman and Travelers arise out of two closely related transactions: the explosion of the heater, and the subsequent loss of the heater. Indeed, Travelers assumed possession of the heater for the sole purpose of determining the cause of the explosion. There is also a significant question of law or fact that is common to the parties. The dominant question is one of fact, whether the loss of the heater caused plaintiffs to be unable to prove their products liability claim against Coleman, and it is common to all the parties. From the record before us it appears that all issues beyond that common question could be readily handled in a single action, without prejudice or inconvenience to the parties.
In sum, joinder and concurrent trials would promote *200fairness and consistency, while conserving valuable judicial resources. On remand and upon a proper request by plaintiffs, the trial court should fully consider whether joinder and concurrent trials are appropriate here. The parties should be allowed to present arguments and evidence that is relevant to this subject.
We further address the dissent’s contention that we should create an evidentiary presumption against Travelers. According to the dissent, we should presume "that the heater was defective” and that Travelers’ "loss of the heater deprived the plaintiffs of their lawsuit” against Coleman. (166 Ill. 2d at 203.) The dissent then concludes that the "only issue which needs to be tried is the issue of damages.” (166 Ill. 2d at 204.) We disagree with the dissent’s view. An evidentiary presumption is improper here for two reasons. First, if plaintiffs can prove their underlying lawsuit against Coleman without the missing heater, then they have not been injured by Travelers’ loss of it. This is entirely possible in the present case because plaintiffs may be able to prove their products liability action against Coleman through circumstantial evidence. (See Ralston v. Casanova (1984), 129 Ill. App. 3d 1050, 1057-60.) Similarly, we can envision several factual situations where a party has negligently lost or destroyed evidence, but that evidence is not critical or even material to a plaintiff’s underlying suit. A plaintiff in this circumstance should not be allowed to recover through the operation of an evidentiary presumption. Second, if Travelers can prove that plaintiffs would have lost their underlying claim against Coleman even with the missing heater, then Travelers has not caused plaintiffs’ injury. A plaintiff should not be allowed to recover with an evidentiary presumption where it can be proven that the underlying suit is meritless. See 166 111. 2d at 196-97.
Before concluding, we address plaintiffs’ claim *201regarding count II. Plaintiffs label count II as "willful and wanton,” but state in their brief that this tort is akin to the tort of intentional spoliation of evidence. They then ask this court to recognize intentional spoliation of evidence as a new tort. Even if we were inclined to do so, count II of plaintiffs’ complaint fails for factual insufficiency. Plaintiffs’ complaint alleges only that Travelers’ agent placed the heater in a closet, and that it later could not be found. It may not be inferred from these allegations that Travelers intentionally destroyed or misplaced the heater. Therefore, count II fails to state a cause of action for intentional spoliation of evidence.
For the reasons stated, we affirm the trial court’s dismissal of count II for willful and wanton spoliation of evidence, reverse the dismissal of count I because it states a cause of action in negligence, and remand this cause to the trial court for further proceedings consistent with this opinion.
Affirmed in part and reversed in part; cause remanded.