Although she looks irreproachable in photographs, Annabel Pitcher's thing is guilt. Her first novel, My Sister Lives on the Mantelpiece, which reaped a harvest of plaudits and the Branford Boase award for a first novel, was narrated by a boy guilty of feeling less than the requisite grief for a dead sister. The narrator of her second book is a teenage girl so riven by guilt that it hurts to go on living because she is, by her own lights, a murderer. In both novels, the bleakness of the material is leavened by Pitcher's uncanny skill with the narrative voice. In each, emotional rawness is modified by ironical humour and dry-eyed directness, which make the voice both convincing and persuasive. Reading Ketchup Clouds, I was reminded somewhat of Meg Rosoff, the non-pareil in this art.

The onset of the book is archetypal: a girl falls in love with two brothers. The younger, Max, is cool at school and apparently available. At a grim party she takes half her clothes off for him and he snaps a photo that does the rounds. The elder, Aaron, is way cooler but apparently unavailable. Guess which one she really loves. Following the implacable logic of Jacobean drama, one of the brothers dies. Because I don't want to diminish your pleasure in reading this book, that's all I'm going to reveal about the denouement. Besides, the way Pitcher unfurls the plot is as interesting as the plot itself (which creaks a tiny bit, to be honest). The novel is made up of letters written by Zoe (not her real name, and from a fake address) to a murderer, Stuart Harris, awaiting execution in Texas. She finds him on a website appealing for pen pals. Unable to confess to a priest, who might just possibly be without sin, she tells all to Harris, who has been found guilty of the crime she's got away with. So this is a one-way epistolary novel, and thus an interesting tease; we are left wondering what an American wife-killer on Death Row might make of handwritten accounts of English teenage shenanigans.

What endeared me to the novel is what another critic might object to: a seeming inconsistency. When Zoe is recounting her tragedy, it's all angst. When she addresses Harris's, it's often with a dark gaiety or gaucheness: "Hey there Stu. Less than two months to go. I wonder if you've marked your calendar with a cross on May 1st or maybe you've just written 6pm lethal injection, and all I can say is I hope you're not afraid of needles because Lauren fainted twice when she had a vaccination at school and almost swallowed her tongue."

At first, I found such passages hugely funny, yet out of tune. In fact, they deepen the complexity of Zoe's feelings for Harris. The nearer he approaches death, the more intimate she becomes. He is not only her confidant but her proxy  it transpires that his wife was having an affair with his brother. Perhaps there is something unconsciously punitive, and therefore self-punishing, in this blithe ghoulishness.

Sadly, this fierce but delicately orchestrated novel ends on a bum note: a letter from the surviving brother to Zoe that is both patronising and mawkish. Its final words ("Spread those strong wings of yours. Fly") brought the wrong kind of lump to my throat. That cavil aside, Ketchup Clouds is risky, confident, compelling and ends, as all prize-winning teen novels seemingly must, with hope for redemption and self-forgiveness. Pitcher should clear her diary for next year's award ceremonies.

Mal Peet's Life: An Exploded Diagram is published by Walker.

 Download the audiobook at audible.co.uk.

Any teenager doing an anxious post-mortem on a Christmas party can take comfort from Ketchup Clouds (Indigo £9.99) by Annabel Pitcher, an honest portrayal of emerging sexuality and the excitement, embarrassment and power games it generates, set in the context of the cost of secrecy and betrayal.

Zoe goes to a party smitten with one boy and leaves smitten with another, setting in motion a chain of events that destroys lives. Unable to confide in her well-meaning but distracted family, she labours under an unnecessary burden of guilt until she finds an outlet for her turmoil in furtive correspondence with a prisoner on Death Row in Texas.

As she shares her intimate world with "Mr S Harris", who soon becomes "Stuart", then "Stu", the Zoe that the world misses (Zoe is not even her real name) emerges as a warm, witty, gifted girl with no need to feel as bad as she does. As in Pitcher's first novel, My Sister Lives on the Mantelpiece, other family members are finely drawn with believable dilemmas and delusions.

A World Between Us (Hot Key £6.99) by Lydia Syson transfers the love triangle to the Spanish civil war, a period underexplored in young adult fiction given the youth of many of the international volunteers who travelled to Spain to fight against Franco.

The stoicism of the underequipped International Brigades and the joys of an unexpected advance, the arrival of longed-for supplies or a rare uninterrupted night's sleep are conveyed as well as the terror and eventual despair that becomes routine.

Jewish East End printer Nat, nurse Felix and journalist George, who travel to Spain separately in 1936, are driven by their own desires as well as by their shared cause.

The core love story, with all its near misses, coincidences and fleeting encounters, is given higher stakes by its setting. Equally absorbing is the relationship between Felix and the untrained Spanish nurse she takes under her wing, revealing the climate of suspicion and fear of "enemies within" that develops as the war grinds on. Syson brings history alive through careful detail.

If Nat, Felix and George believed that they were defeating the forces of evil for ever, Anthony Horowitz's Power of Five crusaders know that the struggle against the Old Ones and their leader, Chaos, has lasted 10,000 years. The series reaches a storming conclusion in Oblivion (Walker £16.99), which is also a satisfying standalone read (although if you hand over the entire series to a Power of Five newbie, you'll have yourself a quiet Christmas).

The fourth book closed with the famous five botching an exit through one of their secret portals. When they emerge in four separate locations (a disaster, because they need to be together to take on the Old Ones) 10 years have passed during their momentary trip, the baddies have let global warming, famine and nuclear terrorism do their work for them and most of the portals are under surveillance.

Holly, the only first-person narrator in this edge-of-the-seat narrative, is not one of the five but her account of growing up in a nuclear winter survivors' village is gripping. Jamie, one of the five, sweeps Holly into the deadly conflict when he stumbles through one of the few unguarded portals, in her village church. This is one of the most satisfying strands of a many-pronged tale, the account of Jamie's brother Scott being "turned" by the son of his former torturer being another. Horowitz offers excitement and emotional engagement on the level of Dr Who at its best.

Maggot Moon (Hot Key £10.99) by Sally Gardner, shortlisted for the Costa children's book of the year, should be gift-wrapped for everyone you know over 10. In her dyslexic hero, Standish, Gardner celebrates dyslexic children as people who love the spoken word ("sweets in the mouth of sound") even as they struggle with the written word ("circus horses jumping up and down").

Growing up in a despised outpost of the Nazi-styled Motherland, but nurtured by Lucille Ball on clandestine American TV as well as by his loving Gramps, Standish is well aware of the wrong that words can do and the fate of those who use words too well, including his missing parents.

When he finds evidence that the Motherland's latest glorious achievement is a warped propaganda exercise responsible for his close friend's suffering (that where there is cheese, there are maggots), he launches his own verbal offensive. For all the wordplay to be savoured, it's the countless truthful moments between individuals that make this book special.

Environmental disasters have become the new vampires in fiction trends, a typical storyline dealing with conflict over basic resources leading to an imbalance of power between totalitarian rulers and their hapless serfs. Novels that tap into anxiety about the future of the planet need something extra to stand out and Richard Masson's excellent debut, Boonie (Hot Key £10.99), has a harrowing opening with echoes of Cormac McCarthy's The Road. In a world where water is more precious than gold, knowing how to find it is an affliction as much as a gift. Published in January for a reflective new year.