The gang follow clues as they search for the Dawn Star, not realising that Ambrose is looking for it, too. Rosamund surprises everyone when she brings an old enemy back to the house.

Hetty and the gang find crucial clues to the Dawn Star, although Flo and Ambrose are now watching them closely and Lady Grenford appears to know more about the diamond than she's letting on.

Lizzie discovers a secret tunnel with a clue, while the gang races Ambrose to find the jewel, and Hetty fears that Ashok is growing too friendly with Lady Grenford.