A novel narrated by an 82-year-old woman with dementia who is searching the neighbourhood for an elderly friend is an unusual choice of subject for a young writer. It could have been grim reading, but Emma Healey has a gift for the kind of dark comedy that can shine through any predicament. There are two timelines woven together: the Elizabeth mystery and the unsolved disappearance of Maud's sister 70 years before. They weave together, mostly successfully, and prove in the end to be connected, via a coincidence that's pleasing, if a little convenient.
The use of Maud as a narrator is at once brilliant and unconvincing. She may behave like a woman with vascular dementia, but expresses herself in her internal voice exactly like a novelist, in beautiful sentences, as if the disease entailed a failure to communicate complex thinking coupled with benign amnesia. A lot of the humour in this gently funny book springs from Maud's unsuitability for the role of investigator, combined with her endearing determination to keep at it. The use of the present tense allows us to inhabit developments minute by minute, alongside our reporter. Healey has a good ear for dialogue, both in the modern and 1940s sections. The postwar family, its culture and the search for Maud's sister are well imagined.
We start with Elizabeth. Elizabeth is missing; Maud knows this because in her pocket she keeps finding notes she's written to herself that say so. There's corroboration for her fears: Elizabeth's house is empty and her coarse and stupid son appears to be engaged in a house clearance. Maud annoys people – notably her stoical, weary daughter, Helen – by insisting that Elizabeth has disappeared (their circular conversations ring absolutely true) and hectors the local constabulary. Maud dottily buys many, many cans of peaches.
That the narrative is constantly engaging is down to Healey's gift for recruiting the minutiae of domestic life into the story. Plaited into this wryness is the darker question, asked in flashbacks, of what can have happened to Sukey, Maud's glamorous older sister, who'd recently married the sinister Frank, who might have been a black-market racketeer. These twin mysteries and their double-helix narrative shape are confidently handled, though the voice of the novel gets itself into a bit of a knot. Inevitably, the interior Maud and the confused old lady she appears to be on the outside don't always seem as though they're the same person. Maud is ill enough to need a carer, the entertainingly pessimistic Carla, but is secretly articulate: Elizabeth has "laughed at my reaction to the veiny ugliness of a moulded leaf or the sick-makingly intricate scales of a fish" in her pottery collection. It's tempting to wonder why a woman constantly writing herself notes – and still able to read them – hasn't also written down the solution to the Elizabeth mystery, which, it transpires, Helen has explained to her over and over again. The sustaining of suspense depends entirely upon the explanations never happening in our earshot.
This is a commendably well-crafted story, and flowers finally into a moving one. The rapid descent of Maud, in the final pages of the book, from someone who can still go shopping on her own to someone who no longer always recognises her daughter, is skilfully done, and there are still flashes of dementia humour. When the law turns up, towards the end, Maud says: "They've been labelled, like my KETTLE plug and my TEA jar. Their label is POLICE."
• Andrea Gillies' The Enlightenment of Nina Findlay is published by Short Books. To order Elizabeth Is Missing for £10.39 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardianbookshop.co.uk.
