Insignificance, Lyceum, Sheffield

They may be based on real people, but the way that Terry Johnson portrays his four characters in his early play, or "thought experiment", Insignificance, they remain little more than puppets.

They may be based on real people, but the way that Terry Johnson portrays his four characters in his early play, or "thought experiment", Insignificance, they remain little more than puppets. No matter how deliciously close the character set-ups, mannerisms and allusions come to representing their real-life models of Albert Einstein, Marilyn Monroe, Joseph McCarthy and Joe DiMaggio, they remain caricatures, parodies even, whose ability to engage with real emotions is strictly limited. Throwing this quartet together ought to prove explosive, but it does little more than tickle our fancy, albeit in an entertaining and vaguely thought-provoking way.

In Samuel West's adept production, his first since being appointed to succeed Michael Grandage at Sheffield Theatres, he has assembled an excellent cast to tease the tangled threads that Johnson has woven out of the unlikely encounter between these four people. Under the threat of being subpoenaed for "un-American activities", a professor prepares to pass the night in his New York hotel room. Enter a bullying senator with the power to make or break the case, and a gum-popping sports star who's only kidding to his sex-goddess wife that he's stupid (yeah?), and Einstein's theories on the shape of the universe take on a whole new dimension. The special theory of relativity? Easy. Add a dumb blonde who "demonstrates" with a toy trucks, a cardboard stooge and three balloons and, hey, we're in business.

"Knowledge is nothing without understanding," remarks Einstein, and, as Johnson is at pains to point out, it is not truth, but merely an agreement, while certainty is little more than illusion. There are other issues, of course. A dark cloud of responsibility for his part in the creation of the atom bomb hangs over the professor; her inability to keep a pregnancy to full term threatens to unhinge the film star; while the ball-player can't hide behind a screen of ignorance forever. And as the complexity of drama, tragic and comic moments, deft dialogue and neat twists and turns of fate are taking place on Tom Piper's bedroom set, the cat's miaow offstage even throws in an allusion (that Johnson added later) to Erwin Schrödinger's scientific theory.

As the professor, Nicholas Le Prevost wears his learning lightly, his baffled air belying his genius. Just as in Johnson's later Hitchcock Blonde, it's the female who suffers most, at the hands of men. Behind that brilliant smile, Mary Stockley makes a vulnerable actress, conveying real pain at what she sees as her deficiencies as a woman. The senator's methods have a ring of horrible truth in Gerard Horan's nuanced performance, his brutality sickening in its plausibility. And before he even enters the bedroom, Patrick O'Kane conveys the pent-up frustration of a husband unable to express himself. Yet it's a remarkably sympathetic portrayal in a production that is beautifully acted, perceptively directed and promises much for the future of Sheffield Theatres under West's directorship.

To Saturday (0114-249 6000); then touring to 9 April