Whilst Charles Marston goes into partnership with Elizabeth to build a South American railway Sarah accepts a marriage proposal from steamboat captain Dampier. Captain Baines sails to France with a passenger, likeable young Thomas Bullen, who saves the life of cabin boy Tom. When Bullen is recalled to England to answer a theft charge brought about by Marston, James, who dislikes his sister's new partner, and Captain Baines are pleased when Bullen proves his innocence. Unfortunately Bullen also, unwittingly, alerts them to the fact that Dampier is a penniless fortune-hunter so James pays him off to leave Sarah.