A young detective's attempts to uncover a group of poachers on Crocodile Island in Florida involve her with kidnapping, reptiles, enemy boats, and a sinister racket.

In a response to a friend’s call for help, Nancy’s father, a lawyer, asks her to travel to mysterious Crocodile Island with her friends Bes and George to study the reptiles and try to uncover a group of suspected poachers. Upon their arrival in Florida, the girls are kidnapped but cleverly escape to pursue their detective work. Dangers mount as they cope with reptiles, enemy boats, and exciting chases after the men who are responsible for a sinister racket that involves many unsuspecting victims. In the end, Nancy makes a bold move to untangle the mass of clues, but she and Ned become imprisoned in the enemy’s submarine and are held for ransom!

In a response to a friend’s call for help, Nancy’s father, a lawyer, asks her to travel to mysterious Crocodile Island with her friends Bes and George to study the reptiles and try to uncover a group of suspected poachers. Upon their arrival in Florida, the girls are kidnapped but cleverly escape to pursue their detective work. Dangers mount as they cope with reptiles, enemy boats, and exciting chases after the men who are responsible for a sinister racket that involves many unsuspecting victims. In the end, Nancy makes a bold move to untangle the mass of clues, but she and Ned become imprisoned in the enemy’s submarine and are held for ransom!

A fiery glowing eye in a museum, the abduction of Ned, the code name Cyclops, and a pilotless helicopter draw Nancy and her friends into a dangerous investigation.

When Nancy and her friends ride deep into the Sawniegunk Forest in search of a flying saucer, they find themselves in the middle of more than one mystery. Wildcats, runaway horses, deadly snakes, and a disappearing Indian keep the sleuths tangled in danger and suspense.

A young detective's attempts to uncover a group of poachers on Crocodile Island in Florida involve her with kidnapping, reptiles, enemy boats, and a sinister racket.