The 'Prince Edward', a Frazer Line ship is put in quarantine by order of strict new medical officer Dr. Darling after its captain,Corcoran,and his daughter fall ill. James is concerned that if he cannot move the ship he will be sued for breach of contact. Lucy dies but ultimately it is shown that she had the plague,caught from fleas on her pet guinea pig,and the Onedins are exonerated. The port is still closed but this is 'force majeure',beyond Onedin's control,so the contract is not broken after all. (thetvdb.com)