An original defendant may not invoke the statutory right of contribution, G.S. 1-240, against another party in a tort action unless both parties are liable as joint tort-feasors to the plaintiff in the action, Hayes v. Wilmington, 243 N.C. 525, 91 S.E. 2d 673; Hunsucker v. Chair Co., 237 N.C. 559, 75 S.E. 2d 768; Lovette v. Lloyd, 236 N.C. *202663, 73 S.E. 2d 886, although the plaintiff himself may, at his election, sue any one or all of the tortfeasors. Pearsall v. Power Co., 258 N.C. 639, 129 S.E. 2d 217; Darroch v. Johnson, 250 N.C. 307, 108 S.E. 2d 589.
“To constitute two or more persons joint tort-feasors the negligent or wrongful act of the one must be so united in time and circumstance with the negligent or tortious act of the other that the two acts in fact constitute but one transaction. While neither concert of action nor unity of purpose is required, there must be concurrence in point of time and place. The parties must either act together in committing the wrong, or their acts, if independent of each other, must unite in causing a single injury.” Shaw v. Barnard, 229 N.C. 713, 715, 51 S.E. 2d 295, 296. (Italics ours.) “(In) order for one defendant to join another as a third-party defendant for the purpose of contribution, he must allege facts sufficient to show joint tortfeasorship and his right to contribution in the event plaintiff recovers against him. * * * In ordér to show joint tort-feasorship, it is necessary that the facts alleged in the cross complaint be sufficient to make the third party liable to the plaintiff along with the cross-complaining defendant in the event of a recovery by the plaintiff against him.” Hayes v. Wilmington, supra at 533, 91 S.E. 2d at 680.
To interplead a third party for contribution, however, the law does not require a defendant in a personal-injury suit to make a judicial admission that his negligence was one of the proximate causes of the injury for which plaintiff sues. He may deny negligence and allege, conditionally or alternatively, that if he was negligent, the third party’s negligence concurred with his as a proximate cause of plaintiff’s injuries. Hayes v. Wilmington, supra. A defendant is not required to be consistent in his pleading. In a personal-injury suit such as this he is entitled to the following defenses, among others: (1) general denial of negligence; (2) sole negligence on the part of the third party; (3) joint and concurring negligence of the third party. Freeman v. Thompson, 216 N.C. 484, 5 S.E. 2d 434. But this liberal rule of pleading is not satisfied when the pleader merely repeats the rule, for it is but a conclusion. An allegation of negligence must give specific information as to the acts complained of, so that the court may determine whether, if established, the acts would constitute negligence. Furthermore, the facts alleged must also show a causal relation between such negligence and the plaintiff’s injury. This is true because actionable negligence “is not a fact in itself, but is the legal result of certain facts.” Stamey v. Membership Corp., 247 N.C. 640, 645, 101 S.E. 2d 814, 818.
*203Here original defendant has sufficiently alleged the facts upon which she relied to establish her defense of additional defendant’s sole negligence; she has not sufficiently alleged, either conditionally or alternatively, facts sufficient to show joint and concurring negligence with Mrs. Strickland. Nowhere does she allege that if the jury should find that she crossed the center line into her left lane, additional defendant, at the same time, did likewise. She never deviates one iota from her allegation that additional defendant alone crossed the center line and collided with her when she was entirely in the lane for northbound traffic (her proper lane). If this be true, original defendant was in nowise negligent; the negligence of additional defendant, being the sole proximate cause of the collision, constituted a complete defense to plaintiff’s action against original defendant. This unamended averment precluded joint tortfeasorship. An allegation that a third party was jointly and concurrently negligent with defendant because she came over the center line into defendant’s lane of travel and collided with defendant on defendant’s side of the road does not establish joint tortfeasorship. The facts alleged will not support the conclusion.
The evidence at the trial followed the pleadings strictly. Original defendant’s evidence tended to show that she, at all times, was on her side of-the road; additional defendant’s and plaintiff’s, that additional defendant was at all times on her right side of the center line. Neither testimony nor physical evidence suggested that either original defendant or additional defendant did any act or omitted to do any act constituting negligence in her own lane of travel. The only issue of fact was, who left her lane to cross the center line? Furthermore, there was no evidence tending to show that original defendant and additional defendant were ever out of their respective lanes of travel at the same time. We cannot, merely because a head-on collision occurred and because each driver claims it to have been the fault of the other in coming into her lane, compromise the case by saying that the collision perhaps occurred in the center of the road, both vehicles straddling the line. Under the pleadings and the evidence in this case, where original defendant and additional defendant each defended only on the ground of the sole negligence of the other, the jury could not answer the first issue, Yes, without exonerating additional defendant. When the jury found that plaintiff was injured by the negligence of original defendant, it necessarily found that she was the one who crossed the center line, and eliminated any question of additional -defendant’s concurring negligence.
For the failure of original defendant to allege and to offer any evidence tending to show that joint and concurring negligence on the part of herself and additional defendant proximately caused injury to plaintiff, additional defendant’s motion for judgment of nonsuit should have *204been sustained. The judgment of the court below, insofar as it awards original defendant contribution from additional defendant, is reversed. This disposition of the case renders moot the judge’s ruling in the supplemental judgment that neither additional defendant nor her liability-insurance company is liable to reimburse original defendant’s liability insurance company for any part of its payment of the judgment which plaintiff secured against original defendant. See, notwithstanding, Pittman v. Snedeker, 264 N.C. 55, 140 S.E. 2d 740; Insurance Co. v. Insurance Co., 264 N.C. 749, 142 S.E. 2d 694.