Billy is an odd boy: his skin's always wrinkled from swimming in the sea, even when it's cold, and he's quiet, different from the other children. Little do they know that he's got David Attenborough narrating his life inside his head, and fish have started talking to him when he's swimming.
Billy's mum's also not very well, and being picked on at school isn't much fun - until he makes a new friend, Patrick, who listens to Billy and fights the bullies with his bear-like strength.
It's purposefully unclear whether the mackerel really are talking to Billy, and taking him along on their beautifully rendered shoal adventures, or whether it's Billy's way of dealing with his mum being ill. However, that silver flash of magic realism really doesn't hurt this wonderful, classic-feeling story at all. At heart, it's a story about friendship in the face of adversity, and Chloe Daykin's writing is clear, poetic and grips you from the start.