
281 S.E.2d 431 (1981)
Danny Ray COLEMAN and Sandra J. Coleman
v.
Norman F. SHIRLEN, Jr. and wife, Jessie Shirlen, Norman Shirlen, Sr., and wife, Reba Shirlen and Ronald Albert Shirlen.
No. 8026SC1074.
Court of Appeals of North Carolina.
September 1, 1981.
*433 W. J. Chandler, Charlotte, for plaintiff-appellant.
Michael P. Carr, Charlotte, for defendants-appellees.
WELLS, Judge.
Plaintiffs first assign error to the granting by the trial judge of the defendants' motion to dismiss for failure to state a claim upon which relief can be granted. G.S. 1A-1, Rule 12(b) provides, however, that if "matters outside the pleading are presented to and not excluded by the court, the [Rule 12(b)(6)] motion shall be treated as one for summary judgment and disposed of as provided in Rule 56 ...." See Smith v. Smith, 17 N.C.App. 416, 420-21, 194 S.E.2d 568, 570 (1973). The trial court's order indicates that it was "[b]ased on the matters presented to the Court, which consisted of the documentary evidence in the Court's file and the statements of counsel...." As the record before us indicates that matters outside the pleadings were presented and not excluded by the trial judge, we must view defendants' motion to dismiss for failure to state a claim for relief, as a motion for summary judgment. Thus we consider only plaintiffs' second assignment of error which was to the trial judge's order allowing defendants' motion for summary judgment.
Plaintiffs' cause of action was based on an alleged civil conspiracy to abduct the child, Martyn Ryan Shirlen, whose custody was vested in plaintiff Sandra Coleman under a separation agreement between Sandra Coleman and Norman Shirlen, Jr. A conspiracy is an agreement between two or more individuals to commit an unlawful act or to do a lawful act in an unlawful manner. Dickens v. Puryear, 302 N.C. 437, 456, 276 S.E.2d 325, 337 (1981); Evans v. GMC Sales, 268 N.C. 544, 546, 151 S.E.2d 69, 71 (1966). To recover under this cause of action, plaintiffs must prove the existence of the agreement between the defendants, that one or more of the conspirators committed an overt, tortious act in furtherance of the conspiracy, and that plaintiffs suffered damages caused by acts committed pursuant to the conspiracy. Dickens v. Puryear, supra; Reid v. Holden, 242 N.C. 408, 414-415, 88 S.E.2d 125, 130 (1955).
*434 On a motion for summary judgment, however, the burden on the moving party is to establish that there is no genuine issue as to any material fact remaining to be determined. Blue Jeans Corp. v. Pinkerton, Inc., 51 N.C.App. 137, 138, 275 S.E.2d 209, 211 (1981). The burden shifts to the non-moving party to either show that a genuine issue of material fact exists or provide an excuse for not so doing, only if the movant carries its burden by showing that an essential element of the opposing party's claim is non-existent. Gregory v. Perdue, Inc., 47 N.C.App. 655, 656, 267 S.E.2d 584, 586 (1980).
The evidence presented to the trial court by defendants on the issues of the alleged conspiracy, abduction and resulting damage to plaintiffs, consists of an answer and affidavit verified by defendants Norman Shirlen, Sr., Reba Shirlen, and Ronald Albert Shirlen. These defendants have clearly not met their burden of establishing that no genuine issue exists as to any material facts. Lacking an adequately supported motion for summary judgment by defendants on these issues, we need not determine whether plaintiffs produced facts, as distinguished from allegations, sufficient to indicate that at trial they could prove, circumstantially or otherwise, the existence of an agreement between defendants to commit the unlawful act of abduction. See Dickens v. Puryear, supra; Edwards v. Ashcraft, 201 N.C. 246, 159 S.E. 355 (1931).
Defendants' answer and affidavit allege and describe a material breach by plaintiffs of the separation agreement. The general rule governing bilateral contracts requires that if either party to the contract commits a material breach of the contract, the other party should be excused from the obligation to perform further. 6 Williston, Contracts § 864, at 290 (3d ed. 1962). Thus, if no valid contract grants custody of the minor child to the mother, then the father's common law right to control his minor child might render the father's abduction of that child legal. See, La Grenade v. Gordon, 46 N.C.App. 329, 264 S.E.2d 757, app. dismissed, 300 N.C. 557, 270 S.E.2d 109 (1980); 3 Lee, N.C. Family Law § 243, at 129-32 (1963). Although defendants' allegations are not contradicted by plaintiffs' papers filed in response to defendants' motion, paragraph 12. of the separation agreement between the parties provides as follows:
12. It is mutually agreed and understood that either party hereto shall have the right to compel the performance of this Agreement, or sue for breach thereof, in the Courts where jurisdiction of the parties hereto may be obtained.
This contractual language implies that the promises contained in the separation agreement were intended to be mutually independent. Failure to perform an independent promise does not excuse nonperformance on the part of the other party. 6 Williston, Contracts § 817, at 32 (3d ed. 1962). Thus the language of the contract itself controverts defendants' assertion that plaintiffs' breach was material. Whether or not plaintiffs' breach was material is a genuine issue of material fact remaining to be determined. See Calamari and Perillo, Contracts § 11-22, at 409 (1977). In their papers offered in support of their motion for summary judgment, defendants Norman Shirlen, Sr., Reba Shirlen, and Ronald Albert Shirlen have not succeeded in demonstrating that plaintiffs' claim is unfounded as to them or that it has a fatal weakness. Gregory v. Perdue, Inc., supra. All of the elements of plaintiffs' claim set forth in their complaint and put at issue by these defendants' answer remain as genuine issues of material fact in the action, to be determined by the triers of fact. We hold that it was error to grant defendants' motion for summary judgment.
Reversed.
HEDRICK and HARRY C. MARTIN, JJ., concur.
