As an irritating nebbish named Kleinman, who gets caught up in a search for a mad killer, he anchors a farrago of generic art-house themes and personalities.
Mr. Frayn succeeds by framing the piece with contributions from Guillaume's East German handler, so the audience is in on the secret from the start, but captivated by how the feeble, nebbish Guillaume worms his way into the charismatic Brandt's confidence.