The historical "what if?" drama, The Night They Burned Washington, will march into Off-Broadway's Theatre Row Theatre for an Oct. 6 opening, following previews Oct. 2-5.

New Yorker Mark R. Giesser's play, which he also directs, is set in the U.S. Patent Office in August 1814, as British troops are advancing on Washington, D.C. Holed up together are an Englishwoman who wants to patent a formula for a "superweapon to end all war," and two bureaucrats, an American sailor and the wife of the French ambassador.

The cast of the fantasy-tinged costume drama includes Avrom Berel, Linda Ewing, Peter Reznikoff, John Wayne Shafer and Marianne Tatum. Designers are John C. Scheffler (sets), Melanie Ann Schmidt (costumes) and Aaron Meadow (lighting). The Night They Burned Washington runs through Oct. 26.

Playwright Giesser, a history buff and former lawyer, was represented Off-Broadway last year with Pledge of Allegiance , set during the early years of the United States. Positive reviews for Pledge have created regional interest for stagings of it in Chicago and elsewhere, reports publicist Alice Herrick (of Cromarty & Company).

Theatre Row Theatre is at 424 W. 42nd Street. For ticket information, call Ticket Central at (212) 279-4200. -- By Kenneth Jones