It is 1658 and England is under the rule of Oliver Cromwell. King Charles is banished, and has sent a messenger to gather support for his plight.

This messenger encounters a simple-minded man named Sidcup Buttermeadow and decrees that he should deliver an important letter. All does not go according to plan, and the help of a kind-hearted barmaid, Nell Gwynne, is required. Help also comes in the form of a ghost, but will the three of them be able to outwit Cromwell and reinstate King Charles?