Frank and Joe Hardy introduce their new mystery.

Iola's purse is stolen, and Frank and Joe track the suspected thief onto Silas Applegate's property. They spot Silas' plumber and hired hand before Silas comes out and orders them off the property.

Rumor of hidden treasure belonging to old Mr. Applegate spurs a summer-long investigation by the Hardy Boys

Joe finds Perry hiding in some bushes. Perry gives Joe a gold doubloon and asks him to hold it, then turns himself in.

The boys find a stash of stolen items from the community in Perry's living quarters. Though he is innocent of the thefts, Perry runs away to avoid capture by the police, when Joe stumbles upon his hiding place and learns the truth.

Rumor of hidden treasure belonging to Old man Applegate, spurs a summer long investigation by the Hardy Boys

The Boys go looking for treasure, and end up inside Applegate's house.

Applegate relates to Frank and Joe how he got the gold and how it was stolen.

Someone digs up Applegate's garden to get Frank and Joe in trouble.

While Frank and Joe wait for their father to get home, Iola goes to the Applegate house to retrieve the pick and shovel.

Hiding from Applegate in the tower, Iola finds Jackley unconscious and tied up. Her screams brings Frank, Joe, and Fenton running.

Fenton discovers Boles, the former gardener, hiding in the tower. The Hardys capture him.

Frank, Joe, and Fenton search Boles apartment while the prisoner taunts them.

Joe traps Boles into a partial confession.

The Boys find a clue they think will solve the mystery of the Applegate treasure.

The authorities look for the treasure in the tower.

The Hardy bunch and police tear apart Applegate's tower structure looking for the stolen treasure.

Frank and Joe spend a day following Boles after he is released from jail - and get another idea of where the treasure is hidden.

Frank and Joe decide to follow Boles after he is released from jail.

The Boys follow Boles back to his apartment but what they see from there leads them to deduce the location of the hidden treasure and bring the case to a conclusion.

Frank and Joe Hardy introduce their new mystery.

Frank angers Joe by spending all day on the phone with girls so Aunt Gertrude sends Joe on an errand with Iola.

Joe and Iola discover several underfed farm animals but cannot find a farmer.

Joe finds muddy footprints and fresh milk while Iola is warned to stay away from the property. Iola alerts Frank.

Joe searches the house and barn. Frank arrives but is spooked while looking for Joe.

While running from the farm, Frank and Joe encounter someone who becomes their new client. Later, they discover what is to become of the animals.

Frank and Joe return to the farm but are soon joined by a man in a truck.

The boys conclude that someone, maybe even a ghost, has been helping the animals. They create a plan to catch a ghost.

The boys' plan to catch the ghost works too well and the ghost wants to know what the boys know about the animals.

Eric finds the boys at the farm and worries he's getting them in trouble. But before they leave, the ghost finds Lacey's will and sneaks it to Joe. Back home, Mr. Hardy and Mr. Binks try to determine its authenticity but Joe isn't so sure.

The boys are brought in after the police discover they removed the animals to avoid them being slaughtered.

Lacey confesses everything to get Frank and Joe out of trouble.

Iola discovers Lacey has had something all along to save his farm.

The animals get loose on the men who came to collect them, just in time to - as the boys and Iola arrive with the proof Lacey can afford his taxes to save them

Lacey has a fortune in old books and manuscripts. Ample money to take care of him and his animals for the rest of their lives.