Plot summary (original edition)

The Hardy boys take on the Twisted Claw smugglers.

Plot summary (revised edition)

While their father Fenton Hardy is working on cases of museum robberies, he asks Frank and Joe to stake out the Black Parrot, a shipping boat docked in Bayport. The Hardy boys get a job loading crates aboard the ship but because the crew is so unfriendly and are kept very busy, they don’t have a chance to investigate. They instead decide to follow another lead and travel to New York to search for a rare old book. While scouring a used book store, they locate a book titled Empire of the Twisted Claw which bears a symbol on the cover which matches a ring the first mate of the Black Parrot was wearing. While they cannot afford to purchase the book, the store keeper allows them to read it, whereby they learn about the Empire of the Twisted Claw and the pirate ships named Black Parrot and Yellow Parrot and the King who controlled the empire.

As the investigation continues, the Boys and their father learn that the thieves are targeting the DeGraw collection and will likely rob six more museums. They stand guard at one of the museums but when the thieves strike, they use a sleeping gas knocking the boys out. Following up on a lead, they find where the Black Parrot has docked again and watch while the crew loads about a dozen logs on board and the ship immediately leaves port. The Hardy boys then track down the Yellow Parrot where they take jobs to get aboard and look around. While investigating more of these strange logs in the storeroom, the logs break free and Frank must hang from the roof to avoid being crushed.

When they learn that the Yellow Parrot is going to meet up with the Black Parrot, the boys realize that they must escape. They jump ship and swim to a strange island where they meet an eccentric man who lives on that island. They escape the island by hitching a ride with a pilot who is a friend of the island man, and thus they can return home. Later, they receive a radio call from someone on the Yellow Parrot who is trying to help them. The boys fly to the source of the signal and find the ship hidden near the strange island. Initially they are captured but manage to escape while learning why the crooks desire the DeGraw collection and capture the masterminds behind the robberies.

Original edition (1939)

• Ghostwriter: John Button
• Summary: The boys go undercover on a pirate ship to defeat the "Twisted Claw" smugglers and reveal their island stronghold.

Revised edition (1969)

• Revision type: Completely rewritten; many plot elements retained.
• Ghostwriter: Tom Mulvey