Harry and his detective classmates try to find clues relating to a mysterious locked closet in Room 3B.

After high school juniors Spencer, Emily, Hanna, and Aria think they have seen Ali, their missing and presumed dead friend, they pursue clues from a mysterious stalker, trying to find out if she is still alive.

Sixth-grader Alton Ziegler loves maps, and when his portfolio of secret maps is stolen, he begins getting notes with orders that he must obey to get the maps back but, with the help of a popular classmate, he just might succeed before his teacher, principal, or someone else learns he has been studying and mapping things about them.

The search for missing gold takes the Hardy boys to the Yucatan Peninsula where they uncover a second mystery.

In order to save the reputation of the Wonderland, P.T. and Gloria must find the culprit who stole a royal tiara from the hotel.

Frank and Joe Hardy are investigating a mysterious old house high on the cliffs above Barmet Bay when they are frightened off by a mysterious scream. The boys return to the apparently haunted house and make a connection between the place and a smuggling case their father is working on. When their father goes missing, they start-out investigating the secret caves beneath the house but soon confront the smugglers.

When a crime syndicate takes over Bayport's reservoir Frank and Joe Hardy help their detective father solve the sinister mystery.

While trying to help a friend out of a difficulty, teenage detective Nancy Drew has a perilous experience in and around a deserted bungalow.

When thieves hijack a collection of stuffed animals from a country auction, Frank and Joe Hardy pursue the getaway car and are drawn into a thrilling mystery. The recently acquired interest of their best pal, chubby Chet Morton, in taxidermy as a hobby adds fresh twists to the puzzle.

The Hardy brothers' visiting Greek pen pal enlists their help in searching for a priceless ancient Greek helmet loaned to and lost by a Hollywood movie company years before.