"The Musical Comedy Murders of 1940" by John Bishop.

The creative team responsible for a recent Broadway flop (in which three chorus girls were murdered by the mysterious “Stage Door Slasher”) assemble for an audition of their new show at the wealthy Westchester estate. The house is replete with sliding panels, secret passageways, and a maid who is apparently four different people—all of which figure diabolically in the comic mayhem which follows when the infamous “Slasher” makes his reappearance and strikes again—and again.