The arrival of Skippy Dies is wonderful news on several fronts. First and foremost, it is at last a new novel by Paul Murray. His debut, the criminally under read An Evening of Long Goodbyes, was shortlisted for the Whitbread First Novel Award in 2003. A hilarious satire of the new Ireland told through the eyes of a clueless young man with aristocratic pretensions, it was also the last we would hear from Murray for seven long years. But now, finally, it’s apparent what he’s been up to all this time: writing the 661 glorious pages of Skippy Dies, one of the most enjoyable, funny and moving reads of this young new year.

Skippy is Daniel “Skippy” Juster, so nicknamed because of his unfortunate resemblance to a certain TV kangaroo. He’s a boarder at Seabrook College, an expensive Catholic school in Dublin, and is at that unfortunate age where “suddenly everyone was tall and gangling and talking about drinking and sperm. Walking among them is like being in a BO-smelling forest.”

Skippy’s best friend is the corpulent computer genius Ruprecht, and the novel opens with Ruprecht and Skippy having a doughnut-eating race at Ed’s, the local hangout for Seabrook students. To Ruprecht’s baffled horror, Skippy collapses off his chair. He isn’t choking, but there’s nothing Ruprecht can do except watch as Skippy writes “Tell Lori” on the floor in doughnut jam before expiring.

The story then rewinds and expands, encompassing not only what Skippy meant and who Lori is, but also Howard the Coward, a history teacher returned in shame from an abortive career in the City. Spending most of his time failing to avoid the obnoxious attentions of the management speak-spouting acting head, Howard lives with his American girlfriend Halley, who fell for him because he was “Irish-looking”, “by which she meant a collection of indistinct features - pale skin, mousy hair, general air of ill-health - that combine to mysteriously powerful romantic effect”.

Howard, though, has his head turned by beautiful substitute teacher Miss McIntyre who, in their first conversation, tells him: “You know, I’m not going to sleep with you.” She does, of course, with disastrous results, especially for the Halloween dance they’re supposed to be chaperoning at the time. It’s at this dance that Skippy finally finds the courage to talk to Lori, an out-of-his-league beauty from girls’ school St Brigid’s across the road. Lori, however, has fallen into a dangerous infatuation with drug-dealing Carl, not so much a school bully as a psychotic criminal in training. Carl doesn’t take lightly to rivals.

This is only the tip of the iceberg. There’s so much more sprawled across these pages, and Murray is terrific at nearly all of it. He’s brilliant, for example, on the painfully poignant combination of credulity and cynicism that defines being 14 years old. Skippy’s classmates will listen with complete belief as Ruprecht discloses his plans to open a door to alternate universes and then say, feelingly, “I wish I was in the 11th dimension. With some porn.”

As with all the best comic novels, though, a dark heart beats underneath, and Murray doesn’t shy away from difficult material. Skippy’s collapse doesn’t appear where you think it will chronologically, and Murray takes the time to explore the aftermath. There is tenderness, too, and heartache and real pain. Ruprecht even uses string theory to prove that the universe might literally be “built out of loneliness”, which is exactly what adolescence feels like.

Is a 661-page boarding-school comedy, no matter how funny or touching, rather too much of a good thing? Perhaps here and there, but for the most part, Skippy Dies is so appealing and surprising that the pages pass with ease. Even better, Hamish Hamilton has very cleverly packaged it as three slim volumes in an attractive box set. One more reason to immerse yourself in a rare tragicomedy that’s both genuinely tragic and genuinely comedic.