In Cornwall in the 1880s, Frederik, once mistakenly apprenticed to a pirate ship, has fallen for Mabel, daughter of the Very Model Of A Modern Major General. For her love he must now defeat his old shipmates (with the dubious aid of a troop of bumbling police).
Young FREDERICK is a slave to duty. By an error on the part of his nurse, RUTH, he was apprenticed (indentured) to a band of pirates instead of pilots. As a slave to duty he serves them to the best of his ability. However, since he turns 21 today, and is out of his indentures, he intends to return to society, and, as a member of society, devote himself to the extermination of the pirates (even though he loves them). Quite a dilemma.
The pirates are not the most successful of raiders and cannot make piracy pay, as they are all orphans and refuse to attack an orphan. Word is out about this weakness and all they encounter claim to be orphans. FREDERICK tries to convince them to return with him, but the PIRATE KING feels that piracy is a more respectable (and honest) profession than the public service. They sail off and leave FREDERICK and RUTH to go their way.
Suddenly, a group of girls arrive. They are MAJOR GENERAL STANLEY’s DAUGHTERS. FREDERICK
is amazed, as, being at sea all his life, he has never seen a girl except for the older RUTH, who, wishing to marry him, always assured him that she was a beautiful woman. FREDERICK asks if there is not one maiden there who will marry him and rescue him from his position. Enter MABEL, who takes him up on his offer. FREDERICK whisks MABEL away, warning the daughters that the pirates will return soon. The Pirates do exactly that, each one taking a daughter and deciding to immediately marry. However, their plan is halted by the entrance of MAJOR GENERAL STANLEY. He pretends to be an orphan and, as such, in need of the comfort of his daughters in his old age. The pirates take pity on him and leave his daughters to him.
That night, in STANLEY’s home, a ruined castle, FREDERICK has assembled a squad of police and their SERGEANT. The police march off and FREDERICK is about to follow when he is stopped by the entrance of a pistol-waving PIRATE KING and RUTH. They tell him that, by a strange paradox, he is still apprenticed to them. He was born in a leap year and, hence, although he is 21, by calendar dates he is really only five-and-a- quarter. They have cleverly appealed to his sense of duty. They exit with him. Now the police arrive, concealing themselves behind furniture.
The pirates arrive to burgle the castle and kill STANLEY whom they have discovered is no orphan. They hide as STANLEY enters. The daughters enter to see why their father is up so late. The pirates reveal themselves, as do the police, and, after a tussle, the pirates have the police overcome. But, when the SERGEANT orders them to yield in Queen Victoria’s name, the pirates do so. It seems that, for all their faults, they love their Queen. They are to be taken away when RUTH explains that the pirates are really noblemen who have gone wrong. They are immediately released to take up their place in the House of Peers, with the rest of the Lords. STANLEY gives away his daughters to them, FREDERICK takes MABEL’s hand and all ends happily.