The Midnight Library sold millions of copies and became the kind of book that appeared in airport bookshops and recovery centers simultaneously. It reached a readership that does not usually track literary fiction releases. Matt Haig’s follow-up to that novel, The Midnight Train, publishing May 26, is described as a sibling work to that book — not a sequel, but set in the same metaphysical territory. The premise trades the infinite library of alternate lives for something more linear: a single train journey between the life someone is living and the life they abandoned, with stops at each significant decision point along the way.