Sarah Moss’s new novel is yet another work of lyrical realism. For a framing device, an italicised and whimsical prologue set in the future. For a story, newlyweds Tom and Ally, separated for six months in the 1880s when hubby goes to Japan. Chapters alternate. Worlds are juxtaposed. Narration is in the present tense – for immediacy or ease? It would seem that things will end badly, but the prologue told us otherwise. At the very last moment this promise is fulfilled. We return to italics for an epilogue.

This might lead one to think that the reader is in for a jading; incredibly, this is not the case. Ally is a recently qualified doctor (one of the first women to be able to take a medical degree) who married late at thirty. Tom is an engineer sent to Japan to lend his expertise to a lighthouse-building project there, while Ally remains behind to put hers to use in a lunatic asylum in Cornwall. This proves the more outlandish path. Tom’s chapters chart how his awkwardness as an uncivilised European in Japan turns to a love of the country and a forgetfulness of his wife; Ally’s follow her painful retreat from battles fought for her career and for her sanity. Choices are just arbitrary enough to suffuse the narrative with a gratifying appearance of autonomy. Characterisation is excellent and the depiction of growing madness defies quotation. Really, this is a sequel to the equally substantial Bodies of Light (2014), and although it can stand alone it will be still better appreciated alongside the story of Ally’s genesis, childhood and medical training.

There are a handful of over-significant chapter endings in the second half – two women say goodbye in a hallway ‘as in the fanlight the clouds drift past the moon’ – but most of the writing is tight and unsentimental, even tough: ‘He does not want to go home. He does not know his wife, not really, not any more. He remembers her breasts in his hands and the smoothness of her back, remembers the satisfaction of entering her at last and then again and again those weeks after the wedding, but any woman has breasts and a back and a place to enter … He does not quite remember why they are married.’

Occasionally, Moss strikes an anachronistic note, as when Ally observes that a friend is ‘able to accept her manifest blessings without opening an existential account, and to do the work to which she is called without holding a running trial in her head.’ Indeed, I was sceptical at first that Ally should seem to have a psychology so recognisable today, but perhaps the greater error is in fact to attribute less complexity to our forebears. In any case, as Moss remarks elsewhere, historical novels are ‘far more about the readers’ and writer’s present than about the past’. What matters is that she gives us what Graham Greene called the ‘revealing phrase’ – and layers of portraiture ‘that will open a door on to yet another human existence’.