
453 N.E.2d 355 (1983)
Doris ORME and Hubert S. Orme, Appellants (Plaintiffs below)
v.
ESTATE OF Nellie KRUWELL, Union Bank and Trust Company As Administrator, Stella White, Everett Mullinix, Roy W. Mullinix, Freda Dysert, Nellie Jo Blessing, John Maurice Mullinix, Dorothy Surface Zaring, Lyndell Surface, Kathleen Surface Hadley, Ruby Dorsey, Dennis McCoy, Lucille Pickeral, Lawrence Smith, Doris Grass, Mae Owens and Deloris Woods, Appellees (Defendants below).
No. 4-383A72.
Court of Appeals of Indiana, Fourth District.
September 13, 1983.
Rehearing Denied October 18, 1983.
Jack Rogers, Rogers & Gesse, Franklin, for appellants.
James R. Acher, Acher & Acher, Franklin, Frank E. Spencer, Indianapolis, for appellees.
CONOVER, Presiding Judge.
Doris and Hubert Orme (Ormes) appeal the Johnson Circuit Court's entry of summary judgment in favor of the Estate of Nellie Kruwell, et al. (Estate).
We affirm.

ISSUE
Does the "contract of settlement" bar the Ormes' recovery?[1]

FACTS
We will set out only those undisputed facts necessary to the disposition of this *356 case. The plaintiffs executed a contract of settlement related to a different suit with Nellie Kruwell in 1951. The agreement included the following language:
It is expressly agreed that the settlement herein provided for ... shall be a full and complete release of any claims involved in this litigation or otherwise between said parties, it being the purpose of said parties to put at rest all claims of every kind or character which now exists between said parties or which may hereafter arise between them.... (Emphasis added).

DISCUSSION AND DECISION
The Ormes argue the contract of settlement did not deal with the real estate involved in this action because the document fails to specifically mention the real estate involved in this action. They rely on our standard of review when summary judgment is brought into question, namely, all doubts must be resolved in favor of the nonmoving party (Ormes). When the same is done in this case, they posit, a genuine issue of material fact becomes apparent.
We disagree.
The language of the release executed in 1952 is unambiguous. It released "all claims of every kind or character," present and future. That language is broad enough to include the Ormes' present one.
Their argument the contract's interpretation is a question of fact is incorrect. Release agreements and contracts generally are interpreted as a matter of law. English Coal Co., Inc. v. Durcholz, (1981) Ind. App., 422 N.E.2d 302, 308. Where the language of an instrument is unambiguous, the intent of the parties may be determined from its "four corners." Parol or extrinsic evidence is inadmissible to expand, vary, or explain the instrument unless there has been a showing of fraud, mistake, ambiguity, illegality, duress, or undue influence. Lippeatt v. Comet Coal & Clay Co., (1981) Ind. App., 419 N.E.2d 1332, 1335; Hauck v. Second National Bank of Richmond, (1972) 153 Ind. App. 245, 286 N.E.2d 852, trans. den'd. (1973).
Affirmed.
MILLER, J., concurs.
NEAL, J. (sitting by designation), concurs.
NOTES
[1]  We have considered the Ormes' other allegations of error, e.g. the existence of various factual disputes, the sufficiency of unverified exhibits to support some of the estate's theories of affirmative defense, and the estate's alleged failure to carry the burden of proof on its affirmative defenses. Even if we ruled in appellants' favor on all issues except the one stated in the text, the undisputed facts require affirmance on the release issue. We will affirm the trial court's granting of summary judgment if it can be sustained on any legal theory supported by the record. Havert v. Caldwell (1983) Ind., 452 N.E.2d 154 at 157. We must affirm on the release issue alone.
