This medieval riot of severed limbs, decapitation and torture begins where Ridley Scott's Robin Hood ends, the signing of Magna Carta in 1215. The appalling revenge that King John (Paul Giamatti) takes on the barons who humiliated him at Runnymede is a topical history lesson in the form of a horror comic. The message is that a tyrant's word isn't worth the paper it's written on.