Following the disappearance of the Moonstone, the celebrated detective Sergeant Cuff is called to Yorkshire by Franklin. A devastated Rachel leaves for London casting suspicion on herself, while Cuff focuses on a servant in the household.

Franklin Blake returns to England after his father's death and seeks out the Verinder family butler, Gabriel Betteredge, to help him recover the famed Indian Moonstone that was stolen the previous year on Rachel Verinder's 18th birthday.

Rachel's cousin Miss Clack arrives at the Verinder House and tells Franklin of the events in London when Rachel and Lady Verinder were reunited and of how another of Rachel's cousins was kidnapped and searched by a group of Indian men.

The Verinder's solicitor Mr Bruff discovers that Rachel has accepted Godfrey's marriage proposal and tries to stop them. After meeting with Cuff, Franklin returns to Yorkshire and he and Gabriel make a perilous trip to the Shivering Sands.

Following a tearful meeting with Rachel, Franklin returns to the Verinder House accepting an offer of help from Dr Jennings - who proposes a re-staging of the events of the night the Moonstone disappeared.