John Taylor lives in quiet solitude, designing puzzles for a living, under the nom-de-plume of 'Ludwig'. When his identical twin, James, disappears off the face of the earth, John takes over his brother's identity in a quest to discover his whereabouts.

David Mitchell, Anna Maxwell Martin, Dipo Ola, Gerran Howell, Izuka Hoyle, Dorothy Atkinson, Sophie Willan, Dylan Hughes