The Passage, By Justin Cronin

Is this vampy doorstopper really one for the ages?

If the publicity machine has done its job (and it probably has; they invariably do), you might have seen or heard a thing or two about Justin Cronin's The Passage by now. Of the many claims made on behalf of this epic, enormous, literary vampire novel – "$3.75m book deal", "the publishing event of the year", "film rights bidding wars", Stateside reviews "unanimous in their praise" – some are even true. But before you sink your teeth into this 780-page-plus beast, there are one or two things you ought to know. The first is that, though this is a long book that sometimes feels longer, it is merely the first part of a planned trilogy. The second is that The Passage is not one book at all, but a trilogy in and of itself.

So all but the most dedicated vampire lovers will need superhuman levels of stamina. But will those without eternal life be rewarded? Without giving too much away, book one uncurls a premise that lives up to the hype; its first line alone, enough to give you the shivers: "Before she became The Girl From Nowhere – The One Who Walked In, The First and Last and Only, who lived a thousand years – she was just a little girl in Iowa, named Amy."

Amy Harper Bellafonte is the only daughter of a young woman whose life has turned her to prostitution. When Amy is six, a trick turns sour, Amy's mum kills him and, on the run from the law, she places Amy in the care of some nearby nuns. Meanwhile, FBI agent Brad Wolgast is rounding up death-row inmates, the archetypal men with nothing to lose, to take part in a secret military experiment involving a virus that transforms those it infects but promises eternal life.

What sets The Passage apart at this stage is the fact that Cronin – until now a writer of literary novels – gives his entire cast 360-degree personalities. We feel for Anthony Carter, the latest death-row "volunteer", because we know so much of his back story. Ditto, the nun looking after Amy, Sister Lacey. Inevitably, Wolgast and Amy's paths cross, the secret experiments go horribly wrong and book one ends with nothing less than the end of the world. Only hold on. Because we're only 250 pages in, and things are about to take a turn for the post-apocalyptic.

Book two, which owes rather too much to Stephen King's The Stand, begins roughly 100 year later. We are in the First Colony, which has formed in the Last City. There are Capital Letters everywhere. At this point, The Passage, un-public-transport-friendly at the best of times, becomes as hard to pick up as it has previously been to put down. Plough on, and you will be introduced to an entirely new cast of characters, some of whom – Peter, Michael, Alicia – you may even care about.

The internal politics of the colony are tiresome, their endless battle against the "virals" now stalking the world outside repetitive, and their love lives and criss-crossing relationships, as fully fleshed and well written as they are, merely another padding device to build the tension. Things only really pick up when Amy returns.

When all's said and done, The Passage is a wonderful idea for a book that – like too many American TV series – knows how good it is and therefore outstays its welcome. There are enough human themes (hope, love, survival, friendship, the power of dreams) to raise it well above the average horror, but its internal battle between the literary and the schlock will, I suspect, leave most readers ultimately disappointed.

My own favourite thing about The Passage is the way it came to be written. While out walking one day in 2005, Cronin's then eight-year-old daughter Iris, a voracious reader, told her dad his books were boring. "What do you want me to write about?" he asked her. "A book about a girl who saves the world... And vampires." So there will be at least one fully satisfied reader for The Passage, then. The rest of us may do better to wait for the film.