Joe Hardy

Frank Hardy

Brothers and primary detective partners, deeply loyal and collaborative.

Chet Morton

Close friends and frequent companions in adventures, with Chet often providing comic relief.

Aunt Gertrude

Aunt and nephew; she is protective and often fusses over the boys.

Biff Hooper

Close friends and fellow adventurers, often working together on cases.

Baldy Turk

Antagonistic relationship; Baldy is a troublemaker who frequently clashes with Joe.

Red Hawkins

Red is a local bully who often antagonizes Joe and his friends.

Pete

Pete is a friend and occasional ally in the boys' adventures.

Tony Prito

Close friends; Tony is a reliable companion on many escapades.

Iola Morton

Joe's girlfriend; they share a sweet, affectionate relationship.

Slim Robinson

Friends and part of the larger group of Bayport teens.

Frank Hardy

Brothers and primary detective partners, deeply loyal and collaborative.

Chet Morton

Close friends and frequent companions in adventures, with Chet often providing comic relief.

The Three Strangers

Joe is present in the boat, joking with Chet and later watching the pursuing craft with suspicion.

Quick Thinking

Engages in a boxing lesson and later teases Biff Hooper, leading to a playful ducking.

A Shady Trio

Eager to join his father's chase, shy around Iola Morton, rides with Frank, and recognizes the three men from earlier.

The Send-Off

Accompanies Frank on the Sleuth, helps with the tarpaulin for the girls, and expresses concern about the weather.

V: No Word from the Chums

Joe accompanies Frank through the storm and to the Morton farm, where he asks about the missing postcard and tries to comfort Iola.

Missing

Supports Frank's plan, expresses worry about Chet and Biff, and helps prepare for the search.

Wreckage

Accompanies Frank, uses marine glasses to examine the wreckage, and expresses urgency to avoid Aunt Gertrude.

The Strange Letter

Joe is present during the search and at home when the ransom letter is discovered, sharing in the astonishment at its contents.

IX: Blacksnake Island

Agrees with Frank's theory and supports the plan to search for Chet and Biff.

The Boy on the Deck

Accompanies Frank, spots Chet on the schooner, and waits in the motorboat while Frank climbs aboard.

The Island

Joe is chased and nearly captured aboard the schooner, dives overboard to escape, and later reunites with Frank.

Into the Cave

Joe uses binoculars to try to identify the men in the motorboat, assists in navigating the island, and grabs a heavy stick to help Frank when the blacksnake appears.

The Four Men

Follows Frank's lead out of the cave and helps spy on the three men.

The Storm

Joe eagerly suggests following the gang and deduces the cave's location relative to the cove; he is focused on rescuing Chet and Biff.

A Startling Announcement

Accompanies Frank, spots the boat, and agrees to follow the gang.

The Alarm

Assists Frank in the rescue, keeps watch at the entrance of the inner chamber, and leads the way out of the cave.

Capture

Captured while helping the injured Biff; recognized by Red as one of the boys from the boat.

Back to the Cave

Joe breaks his rusty handcuffs against the rock, then retrieves the keys from the passage shelf and frees the others.

XIX: Separated

Assists Frank in the escape, helps find the trail, and fights off a gangster who tries to board the boat.

Seizing the Boats

Assists Frank in seizing the boats, handling ropes and anchors, and spots the Napoli.

The Chase

Awaits aboard the revenue cutter with Frank.

Home Again

Participates in the rescue and reunion with his father.