Out of Breath, by Julie Myerson; Monster Love,by Carol Topolski

Everybody from Tolstoy to tabloids knows that only unhappy stories are interesting. But in Julie Myerson's new novel we have childhood sexual abuse, childhood cancer, divorce, abandonment and pursuit by an axeman; in Carol Topolski's, we have childhood sexual abuse, parental cancer and death, and insane parents (OCD, bipolar, a possible infanticide) producing insane, infanticidal children. Have we, perhaps, gone too far?

Well, both are what we might call Larkin novels ("they fuck you up, your mum and dad"). Nonetheless they are different, and may deliver different answers to my question.

Out of Breath is a mythical rite-of -passage novel, following 13-year-old Flynn through her first encounters with love, death and difference. One day she sees Alex standing still and silent as a wild animal at the bottom of her garden. She is instantly attracted; and soon she and her brother Sam run away from home (divorced mother, absent father) to join him.

Flynn is anxious and insecure, and Sam is going off the rails into drink and drugs; but Alex and his friends know real trouble. They have fled from care homes and foster families, where Diana has been sexually abused and given birth to Joey, Alex has become fatally ill (vide childhood cancer), and Mouse, who is only six, has also been abused by Joey's father. He is pursuing them (vide axeman); and now all six youngsters flee together. As Flynn moves out of childhood and into the knowledge of love and death, their journey becomes ever stranger and more symbolic, until it becomes clear that part of it at least has been her dream. In the end she returns them all to reality, and to a traditional happy ending. The axeman-abuser is punished, Alex recovers, Diana and Mouse find homes, and Sam and Flynn are back in touch with their father.

Monster Love couldn't be more different. It starts with horror and gets worse. In an empty house in a smart suburb, four-year-old Samantha is found dead in a cage. Through many circling voices we close in on the murderers: Samantha's own parents, Sherilyn and Brendan. We hear from a neighbour, a social worker, a policeman, the judge and a juror at the trial, a fellow-prisoner and several prison officers, their parents, themselves.

So we learn their monstrosity - in detail, I warn you - and what made them monsters: appalling psychological and sexual abuse by their own parents (apart from Brendan's mother, the one who gets cancer and dies.) The result is the monster love of the title: not Myerson's normal, difficult adult love, for which we must leave our childhood gardens; but a huge mad love, a pathological extension of self-love, so not really love at all.

This vision of monster love seems to me true – and not only of sick individuals, but of sick groups and nations. Much else in this novel is also true: the way an evil act destroys not only the victim, but many others as well; the way it brings men face to face with their own capacity for violence. Monster Love doesn't explore how Brendan's and Sherilyn's parents came to be the monsters they are, but no doubt in the same way. As Larkin (almost) said, evil spreads like a coastal shelf; and by the end of this novel you'll accept his conclusion wholeheartedly: don't have any kids yourself.

So Monster Love is thoroughly depressing. It is also a first novel by a psychotherapist – and, though an impressive debut, it shows. Some of the writing is unsubtle (Brendan's and Sherilyn's repeated echoes of each other) and, though the thèse dominates the roman, I wasn't quite sure, in the end, what it was. It's not only the murderers themselves who believe that they are in telepathic communion, for instance – so do several of our most reliable witnesses and so, in the last pages, does the novel itself.

Is Topolski saying that horrific abuse makes people not only subhuman, but superhuman as well? That would be a worrying message and, unlike the other, not true.

Julie Myerson, by contrast, is a skilled literary writer, and Out of Breath is a more mysterious, multi-layered, literary novel. It is also less depressing. But its characters are standard (sensitive girl, selfish brother, brave sick romantic hero), and its happy ending absurd. Monster Love's normal characters (the social worker, the courtroom and prison people) are from central casting, too. But for all its faults, it is a brave book. To answer my question: both pile on the horror, but in Monster Love it's part of the point, while in Out of Breath it isn't. So you'll enjoy Out of Breath more – but it's the one that goes too far.

Carole Angier's biography 'Primo Levi: the double bond' is published by Penguin