The ''Maggie'' is a typical Clyde puffer, a small, aged cargo boat with a varied, irascible and argumentative crew. MacTaggart (Alex Mackenzie), her rascal of a captain, is in dire need of £300 to renew his licence. In a shipping office in Glasgow, he overhears Mr Pusey (Hubert Gregg), an Englishman complete with bowler hat and umbrella, trying to arrange for the transportation of some personal furniture for his boss, American Calvin B. Marshall (Paul Douglas (actor)). The big, reputable shipping company has nothing immediately available, so MacTaggart gets the job when Pusey mistakenly believes that he works for the company and that the more modern vessel docked next to the ''Maggie'' is MacTaggart's.