Death in Shetland Waters

Cass Lynch has achieved the post of third officer aboard her beloved ship. On their latest voyage it seems there's a stowaway aboard, yet a search finds nobody. Then a trainee goes missing. Cass and DI Gavin Macrae find themselves up against a ruthless killer. Cass also has a dilemma: could she bear to give up the sea for a settled life with Gavin?