Snagglepuss visits Jolly Olde England and is instantly motivated to become a Knight of the Round Table.

Hildy, the journalist former wife of newspaper editor Walter Burns, visits his office to inform him that she’s engaged and will be getting remarried the next day. Walter can’t let that happen and frames the fiancé, Bruce Baldwin, for one thing after another, to keep him temporarily held in prison, while trying to steer Hildy into returning to her old job as his employee.

A mouse is annoying the family of Mr. and Mrs. Evil J. Evil, the scientists, and Snagglepuss is offered food and lodging if he will get rid of the pest. The trouble is that the Evil's little boy has been experimenting with the mouse, and the furry rodent is now six feet tall!