Lady Dona St Columb lives at court in London with her pleasant but dull husband Harry and their two small children, while having the odd mild flirtation with Lord Rockingham. One night she and Rockingham dress up as highwaymen for a joke, and badly frighten an elderly lady. As a result she is thoroughly ashamed of herself and the utterly boring life she is leading. As a result she decides to make a complete break and takes herself plus the children, but minus Harry, to his Cornish estate at Navron.
On arrival she finds it closed, with just William, a manservant in residence. She finds the area very peaceful but for the warnings of Lord Godolphin, another local landowner, that French pirates are around and threatening to rob everyone in the neighbourhood. Then she finds that William is secretly working with the pirates. While exploring the area she accidentally discovers their ship, is captured by them and taken on board.
She gets on well with the pirate leader, and is told she can come and go from the ship as she pleases. As their friendship deepens, she learns that he was a wealthy landowner in Brittany but like her he wanted to turn his back on a boring privileged existence. When she finds that Godolphin and his neighbours are keen to bring the pirates to justice and want her help, just as Harry and Rockingham come to Navron to look for her.
This report prepared by John Van der Kiste