This is a story of a family — especially two sisters — and things that brought them together and pushed them apart. It varies between straightforward realist events, and ambiguous, almost fantastic scenes, which may be memories, or partly memories, or a way for the character to deal with memories.
It’s part of a series that Bernardine Evaristo has curated for Penguin, called Black Britain: Writing Back, aiming to bring lost works back into publication. This one won awards back in 1997 (even though, confusingly, the copyright date is 1998). It’s been out of print since.
Worth checking out.