What We Can Know

What We Can Know is a novel by the English writer Ian McEwan, published on 18 September 2025 by Jonathan Cape. It is his eighteenth novel.

The book has two halves. The first takes place at a dinner in 2014, where the poet Francis Blundy reads a poem called A Corona for Vivien in honour of his wife's birthday, and the reader is given the scene as it happens, including everything the guests miss. The second is set in 2119, in a UK partly under water after rising seas and a nuclear accident, where Tom Metcalfe works at a university and has devoted himself to the lost poem. The novel is about the gap between what happened at the table and what can afterwards be known about it, and the research in the future half is the means by which the reader is shown how much of the past cannot be recovered.

McEwan has written about science and the law throughout his career, and this novel extends his interest in what evidence can establish into a setting a century ahead.