"Life's like a train journey. That's what they say, isn't it?" In Winsome Pinnock's new play, one man's life and another's train journey come to a grisly end, when a passenger throws himself in front of a Tube train. Impelled by guilt, train driver Cyrus hunts for clues to the tragedy in the life of the man he's killed. Meanwhile, Pinnock replays suicidal Sonny's last day, as he invites a woman he's never met on the strangest, happiest date of her life.
One Under is about the parental bond, and the ways it can be severed. Cyrus is convinced the dead man was his long-lost son. The rootless, adopted Sonny believes he has killed a child, in a drink-driving accident. To atone, he seeks out bereaved mother Christine and tries to "give her a piece of myself. But I couldn't, because there was nothing there." The wounds left by the sundering of parent and child cannot easily be healed.
One Under is a whydunnit, in which we accumulate information linking the characters and explaining Sonny's death. With its complex time structure and symmetrical plotting, the play's twin tracks merge and separate like the Circle Line at rush hour. On one hand, this chopped-up chronology helps disguise the story's inconsequential ending. It also means that, for too long before their motives are revealed, we've no idea why Sonny and Cyrus are behaving so cryptically. To explain Sonny's family's tolerance of the seemingly delusional Cyrus, and Christine's susceptibility to her evasive suitor, I'd have welcomed an announcement: mind the credibility gap.
Pinnock's dialogue doesn't always help: it can sound stilted and leaves too many questions. On an unprepossessing Underground set, Jennie Darnell's production struggles to raise the dramatic temperature. But there are some strong performances, from Brian Bovell as the tube driver who can't find the light at the end of the tunnel, and Geoffrey Burton as the cleaner who "married three different women, but them all turn into the same wife".
· Until March 5. Box office: 020-7328 1000.
