Jane Austen, novelist and private investigator, is back on another case, this one involving the Royal Navy. Her brother Frank's friend, Tom Seagrave, is in the brig, accused by his first mate of stabbing a French captain after the captain surrendered. Tom denies the charges, but his dagger was found in the French captain's chest. To clear up this mystery, Jane agrees to go to the Wool House, a building where French prisoners are jailed.