Queen's bounty - Fiona Buckley

Happily married to her third husband, Ursula Blanchard is rudely shaken on receipt of a threatening letter from the exiled Anne Percy, Countess of Northumberland, whose treasonous plot against Elizabeth I, Ursula helped foil a few months previously. Ursula dismisses the Countess's letter as idle threats, but then a series of strange events rocks Ursula's household - and Ursula herself is accused of witchcraft. Could Anne Percy really be orchestrating a plot against Ursula from her exile in the Netherlands?
And, if so, how can Ursula prove it before she is hanged as a witch?