Herman's Hermits travel to England for a high-stakes greyhound race.

When 20-year-old Herman Tulley inherits his grandfather's most prized possession, a greyhound named Mrs. Brown, he and his friends (Barry, Keith, Karl, and Derek) decide to make their fortune racing the dog. After the animal has won the Manchester heat of the National Greyhound Derby, Herman meets wealthy Londoners Mr. and Mrs. Brown and their daughter Judy, a model. Hoping to see Judy again, Herman and his pop-singing friends decide to take the dog to London for the derby finals. Once there, however, they are swindled by a con man who takes all their money. Fortunately, the Honorable Percy Sutton, a good-natured tramp whom Herman once befriended in Manchester, appears and finds them beds for the night. The following day Mr. Brown gets them jobs as fruit-peddlers. Judy, who is attracted to Herman, invites them to a party, where they are offered a nightclub engagement. The next day, Herman's greyhound wins the preliminary heat of the London Derby. But Herman's enthusiasm turns to gloom when Judy goes to Rome for a 6-week modeling assignment, and the greyhound disappears at the station. After a futile search, Herman and his friends return to Manchester. Herman's spirits pick up when Percy arrives with the lost dog, and Herman discovers that his tomboy neighbor Tulip has become a very attractive woman. When Herman's dog gives birth to a mongrel pup, Herman and his friends give the pup to Judy's mother, the other Mrs. Brown.