Everything under / Daisy Johnson.

As a child, Gretel lived on a canal boat with her mother, and together they invented a language that was just their own. She hasn't seen her mother since the age of sixteen, though - almost a lifetime ago - and those memories have faded. Now Gretel works as a lexicographer, updating dictionary entries, which suits her solitary nature. But a phone call from the hospital interrupts Gretel's isolation and throws up questions from long ago. She begins to remember the private vocabulary of her childhood. She remembers other things, too: the strange lonely boy who came to stay on the boat one winter; and the creature in the water - a canal thief? - swimming upstream, getting ever closer. In the end, there will be nothing for Gretel to do but go back...