In the north of England, a silver cup has been stolen from Marsden Hall...Meg the serving girl will hang for it, unless she agrees to spy on her friends at the Black Bull Tavern.

Her friend Will Marsden is desperate to save her. As Meg and Will struggle with the dilemma, Will's mother tells them a story she has kept secret for years: how she herself, as a young lady-in-waiting, was forced to spy on Mary Queen of Scots.

Two stories of spies and double-dealing intertwine in Terry Deary's exciting tale of adventure set in Tudor times.