Dick Young is lent a house in Cornwall by his friend Professor Magnus Lane. During his stay he agrees to serve as a guinea pig for a new drug that Magnus has discovered in his biochemical researches.
The effect of this drug is to transport Dick from the house at Kilmarth to the Cornwall of the 14th century. There, in the manor of Tywardreath, the domain of Sir Henry Champernoune, he witnesses intrigue, adultery and murder.
As his time travelling increases, Dick resents more and more the days he must spend in the modern world, longing ever more fervently to get back into his world of centuries before . . .