I have a theory. It goes something like this: Martin Scorsese lost the plot just about the time he forgot his films needed a pivot. Think about it. Mean Streets had Charlie. Taxi Driver, Travis. King of Comedy? Rupert. Raging Bull? The Bull himself, raging Jake LaMotta. That focus - that pivot - around which the rest swing. And it's not just there in the writing; you need a performance too. Negative evidence: Age of Innocence, Kundun, Color of Money, Cape Fear. And, sadly, Bringing Out The Dead.

It could be a lot of things, but at this stage let the jury convict Nic Cage. New York, early 90s. A hollow-eyed Cage is Frank Pierce, an insomniac ambulance driver passing the graveyard shift in Hell with the crazies, druggers, hookers and cardiac cases. ER can't cope and half the patients either don't want to stay there or even stay alive.

There's little plot to Paul Schrader's screenplay (from an overwritten, under-imagined novel by Joe Connelly). It's a snapshot whose only through-thread is Mary (Patricia Arquette). Frank took her father in from a heart attack and there's the suggestion of tentative romance amidst all the violence and the blood.

But Cage - let alone Arquette, whose performance is so absent she could have phoned it in - can't hack it. He's a light comedian out of his depth, mistaking mannerism for God's lonely man. With the centre adrift, the effect is to throw the spotlight on his co-drivers. Of those, John Goodman struggles to make something out of playing essentially nice, and the cigar-chomping Ving Rhames has his moments, but it's only riding shotgun for the scary Tom Sizemore that the movie really comes alive. It's here, with The Clash competing with the siren, the lights strobing and Sizemore as likely to put passers-by into hospital as take them there, that Bringing Out The Dead achieves the sensory pile-up it forcefully argues for. Elsewhere, heresy of heresies, the score just sounds exactly like a soundtrack and even Thelma Schoonmaker's editing feels slack.

In the final analysis, Bringing Out The Dead is too much like Taxi Driver remade by an unenthusiastic Spike Lee (just as Lee makes his most Scorsese-like picture in the vigorous and much better Summer of Sam). Schrader's screenplay injects some humour, but its soul-searching feels trite and confused. Deft digital trickery allows Frank to repeatedly see one of his young fatalities in every face on the street, but we've no emotional investment in his loss and the results feel heavy-handed. "No one asked you to suffer," Mary tells him, "that was your idea." Too much of this half-hearted, miscast picture looks like someone else's idea.