The Mousetrap, Broutil & Frothingham Productions, at the Theatre Building Chicago. Agatha Christie’s unkillable 1952 murder mystery could never have lasted half a century if she weren’t so adept at exploiting our fear of the unknown, capitalizing on our ambivalence about strangers who share the same shelter. And Susan Padveen’s taut, crackling staging casts a spell from the start, with set designers Jacqueline and Richard Penrod’s sepulchral Great Hall of Monkswell Manor. This Berkshire guest house, just opened for business and ripe for mayhem, is run by newlyweds in over their heads, coping with four bumptious guests, one uninvited foreigner, and a detective. Complicating the situation are a blizzard that snows everyone in, a phone line that’s been mysteriously cut, and a roving murderer bent on revenge and inspired by the nursery jingle “Three Blind Mice.”