The continuing adventures of the boys from "Doctor In The House", "Doctor At Large" and "Doctor In Charge". When Dick (Geoffrey Davies) finally gets himself the sack from St Swithin's, Duncan (Robin Nedwell) resigns in support. They sign up for what they hope will be a cushy job as medical officers on the cruise ship MS Begonia. Unfortunately they didn't realise Professor Loftus' twin brother would be the captain!