Assassins, Crucible Theatre, Sheffield <!-- none onestar twostar threestar fourstar fivestar -->

"If you keep your goal in sight,/ You can climb to any height.../ Everybody's got the right/ To their dreams." This is standard Broadway sentiment. The twist in Sondheim's 1991 show is that the song is delivered by a line-up of nine gun-toting would-be assassins of US presidents, ranging from Lincoln's nemesis, John Wilkes Booth, to John Hinckley who tried to put an end to Ronald Reagan.

Sondheim confronts us with the apparent incongruity of placing these people in a piece of musical theatre, only to invite us to see that the clash is more apparent than real.

The "you can be a winner" ethos of the American musical is the product of a culture in which, theoretically, anyone can grow up to be President. For Sondheim and John Weidman (who wrote the book), it follows that when some losers discover that this is a cruel myth, they will aim - with a gun - for the biggest consolation prize. The assassins demonstrate the dark downside of the same tradition that formed the men they tried to murder. They take to a psychopathic degree the furious self-assertion often found in musical protagonists (think Gypsy's Momma Rose with firearms - and duck).

The small-scale New York premiere had the misfortune to coincide with the Gulf War. On the grounds that it "was not an appropriate time" to ask audiences "to think critically about various aspects of the American experience", a projected Broadway revival was swiftly cancelled in the wake of September 11. Not until three years later did Assassins find a home on the Great White Way in a Tony-garlanded revival.

Nikolai Foster's Crucible production is the first large-scale account of this work in Britain since September 11. Has that watershed altered our perception of Assassins? The first thing to say is that Foster has created a powerfully atmospheric piece of theatre. The show unfolds in a spooky out-of-time fairground, dominated by a tilting wall of roller-coaster scaffolding festooned with TV screens flashing a gallery of presidential heads. The assassins emerge eerily from the audience, as the barker lures them down to this twilight zone to try their luck.

The singing is overamplified and, for my taste, the Balladeer (Matt Rawle), who offers a folk-mode commentary, loses perspective by getting too involved. But, by and large, cast and band do justice to Sondheim's score, which takes signature American forms and mordantly distorts them or subversively shifts them to unfamiliar contexts.

Barbershop harmonies celebrate the wonders of a gun. A Carpenters-style number embarrassingly overheats as Hinckley (James Gillian) and Lynette Fromme (Penny Layden) swear cracked devotion to (respectively) Jodie Foster and Charles Manson. Ian Bartholomew as Charles Guiteau cake-walks to the scaffold with an increasingly desperate confidence.

This figure, who wrote a book called The Truth and believed his suicide mission was God's will, feels much more topical post-September 11, as does Samuel Byck, a nutter in a Santa suit (splendidly played by Gerard Murphy), who tried to hijack a jetliner in order to "drop a 747 on the White House and incinerate Dick Nixon". You can see how both these men - in the way they twisted feelings of powerlessness and humiliation into a murderous political project - have affinities with some of today's terrorists. But does this not give the lie to one of the fundamental propositions of Assassins - that there is something distinctively American about the mind-set of the killers and its formation?

There are some wonderful sequences. As Czolgosz stands in the queue at the Pan American Exposition, the Balladeer sings that "in the USA... you can work your way/ To the head of the line" - which sounds very meritocratic until you realise that he's jostling forward to murder President McKinley. But the show is too inclined to make light of the huge differences in the assassins' motivation, and post-September 11 it is beginning to look off target.

To 1 April (0114-249 6000)