It is 1566 and Mary Queen of Scots is in residence at Craigmillar Castle. But as rumours of treasonous plots abound, no one there can feel safe. Least of all Lord James Bothwell, who survives an attack thanks to a lad by the name of Will Fellows. What is surprising is that Will snatched the diamond-encrusted dagger from a woman, who then disappears into the night.