Juste avant 'Oubli is about love, and about writing. Judging from Zeniter's remerciements (Acknowledgements) the germ of the book is in her uncompleted thesis on the playwright Martin Crimp's representations of women. The novel is set on the imaginary Hebridean island Mirhalay, where the imaginary detective novelist Galwin Donnell spends the remaining last few decades of his life, following his divorce, in isolation until his apparent suicide in 1985.
Franck is a Frenchman and a nurse convinced that his forename has led him to a life of obscurity. After three months, he joins his girlfriend on the island, hoping that she will spend the rest of her life with him: Émilie has given up her teaching job to work on a thesis on Galwin Donnell's representations of women, and Franck (whom Émilie has upgraded to medical doctor status to her colleagues) is organising a seminar on Donnell on the island.
So we are treated to an idea of the series of lectures on Mirhalay, details of most (if not all) of ten novels involving the sex-addicted detective Adrian Dickson [!] Carr: Donnell's writing can be somewhat controversial as there are intimations of paedophilia in Carr's girly interests. And there are a number of footnotes to fictional books, plus (in sans serif type) a copy of a fictional Wikipédia entry of Donnell's use of the expression 'porc-chien' (or 'dog-pig').
Galwin Donnell begins to take over Émilie's mind, and therefore greatly intrudes on her relationship with Franck, who finds a kind of solace in the warden Jock, now the only permanent inhabitant on the island. Jock, though, has his own problems, not the least of which is his isolation, and he has built a sound-proof room in which no water or birds can be heard.
Jock, an alcoholic and a nihilist, is in no respect an idiot, and his knowledge of the island and its history (if not the world outside it) is most profound, and as an outsider to an outsider, he befriends Franck, who is very frank about his lowly academic medical status. And Jock is very frank too, even to the point of 'admitting' (maybe falsely) that as a ten-year-old he pushed Galwin Donnell to his death.
And then Jock kills himself, leaving Franck to do what he wants with to Donnell's missing (and never read) last chapter of his final novel. Well, what do you do when you find a precious manuscript?