When a Mennonite pastor visits Elf in hospital, to 'pray together for her soul', Elf performs a striptease while reciting Philip Larkin's 'Days'. Even in the story's closing stages, comedy and tragedy harp on the same tune. Both sisters are lovable, exuberant, quirky, in many respects mirror-opposites. The story is told in running sprees of dialogue without quotation marks: we experience everything as it is heard in Yoli's mind. He had 77 dollars on him at the time and we used the money for Thai takeout because, as my friend Julie says about times like this: You still have to eat.'

The worst that can happen has already happened: 'My father died beside trees on iron rails. I didn't throw the phone into the river.' In the novel's zany world, life and death fence on the rim of the void. In this whirligig of ecstatic kinesis, negatives tumble head over heels into positives, only to flip into new negatives: 'I hung up and threw the phone into the river. Yoli says it makes her sad, too, but happy. Yoli, at Elf's hospital bed, shows her sister a tattoo she's been trying to remove: 'a jester, an old-fashioned harlequin'. Nevertheless, as I read, I laughed aloud even as tears rose in my eyes. She's terrified that it will break.' Starvation, pills, slitting her wrists, drinking bleach: none of this is remotely funny. But in adulthood, this gifted woman detects the presence of 'a glass piano inside her. In the Mennonite East Village, pianos are anathematised by a patriarchal community 'rigged for compliance' from childhood, Elf rebels.

Paradoxically, Yoli's life is a mess, but Elf is a concert pianist, beautiful, married to a lovely man and both sassy and original. Sisters Elfrieda and Yolanda, the novel's narrator, are the tumultuous children of a Canadian Mennonite community, 'enemies who loved each other' – for while Yoli is pledged to keep her sister alive, Elf is determined to die.

Can a work of mourning be a comedy? Uniquely, Toews (pictured below) has created a requiem with an antic disposition. Toews has acknowledged its autobiographical source: her father's suicide, explored in the biography Swing Low: A Life (2000), was followed by her sister's 10 years later. Its compulsive readability is all the more remarkable since the story issues from such a dark place in the author's heart. I can think of no precedent for the darkly fizzing tragicomic jeu d'esprit that is Miriam Toews's sixth novel.

All my puny sorrows by miriam toews