The Truelove — Patrick O'Brian

A British whaler has been captured by an ambitious chief in the Sandwich Islands at French instigation, and Captain Aubrey is dispatched with the Surprise to restore order. But stowed away in the cable-tier is an escaped female convict. To the officers, Clarissa Harvill is an object of awkward courtliness and dangerous jealousies. Only Aubrey's friend, Dr. Stephen Maturin, can fathom Clarissa's secrets: her crime, her personality, and a clue identifying a highly placed French spy in London.