In the spring of 1820, Captain Brandon Alexander Trevaline, a veteran of Waterloo and the last scion of an old and distinguished family, was accused of dishonoring the wife of the local Squire. Despite his firm denials, nothing less than a duel would salve the Squire's pride. Accordingly, a meeting was arranged at the ruins of Trevaline Castle one morning to settle the matter as gentlemen did.

But the Squire was dissatisfied with the outcome and enraged beyond reason. Bare seconds after proving his honor, Brandon Trevaline was shot in the back by his defeated opponent. Only then did the truth emerge. The Squire had murdered an innocent man. The last of an ancient line had died without issue and the Trevaline Estate passed to a distant cousin, Martin Collins.

But contrary to all his expectations, Martin Collins inherited only the Trevaline lands and a mountain of debt. The fabulous collection of Trevaline jewels, preserved by the family since Tudor times, was missing and believed irretrievably lost. Though generations of Collinses searched diligently for them, the jewels were never found. Only the signet ring Brandon had been wearing the day he died remained in the family's possession.

And a legend slowly grew in the nearby village that Brandon Trevaline's ghost still walked the ruins where he had died.

Two hundred years later, Brett Saunders comes to the venerable old mansion for a week-long visit with her good friend Suzette, a distant descendant of Martin Collins. Suzette's family welcome her warmly, especially Suzette's brother, Andrew, who shows a sudden interest in his little sister's friend.

The day after her arrival at Trevaline, Brett takes a solitary trip to explore the old castle ruins. Through the impetus of a fall from her horse, she encounters Brandon's ghost and discovers that his story is far from over. Aware of the fabled bad blood between Trevaline and Collins, she is initially concerned at what she has inadvertently woken, but Brandon eases her fears.

When the ruby signet ring is discovered missing that very evening, however, Brett becomes suspicious of her charming ghost's good intentions.

But Brandon is not the thief and Brett is not immune to his impudent charm. As she and the ghost grow closer in their attempts to get to the bottom of the mystery, Suzette's father calls in Scotland Yard.

And the tangled web grows thicker.