Agatha Christie’s Witness for the Prosecution has more twists than a Shyamalan movie. The play’s surprise ending has kept it running for 53 years and counting. “Since the time this play was first produced in the West End, a placard in the lobby asked audience members not to reveal the outcome to those who hadn’t seen it,” says Mark Shanahan, who plays Leonard in the Alley’s production. “That contract is very important in mystery theater. Just when you think the play is over, Christie changes the world on you.”

The courtroom drama and thriller centers around devil-may-care drifter Leonard Vole, who’s on trial for the murder of wealthy widow Emily English. Things heat up when, while testifying, Leonard’s wife, Romaine, drops a cataclysmic bombshell on the entire case (the first of three major plot twists). “It’s a whodunit and a good old-fashioned English murder mystery, but it’s also an epic battle of wills,” explains Shanahan.

Good luck in figuring out whodunit, even if you have an eagle eye for mystery. Says Shanahan: “There is an incredible amount of sleight of hand distracting you from information which might be right under your nose.” See if the judge agrees when Witness opens at 7:30 p.m.

May 13-June 11