A robbery at the local museum seems to be connected with the death of a local forger, and Lovejoy goes on the trail of a hoard of Roman coins in the Isle of Man. Two Americans are also after the coins.

Sam Wendell, an old forger, dies of a heart attack while being pursued by a mysterious priest, leaving behind one of his small forgeries. Sam had told his wife it was the key to a fortune, and the priest soon tries to break into the Wendell house. Lovejoy aims to unravel the puzzle, by way of helping Sam's widow (who's left with very little) to recover anything of value. Along the way, Lovejoy dresses up as a priest.

Lovejoy finds a bundle of old love letters hidden in the back of an antique clock. He quickly falls for the owner, but are the letters genuine? Under the name of 'Captain Lovejoy', he sets out to find the answer.