Dink Duncan and his two friends investigate the apparent kidnapping of famous mystery author Wallis Wallace. A is for author ... Dink writes to his favorite author, mystery writer Wallis Wallace, and invites him to visit Green Lawn. To Dink's amazement, Wallace says he'll come! But when the big day arrives, Wallace is nowhere to be found. The police think he just missed his plane, but Dink suspects foul play. It's up to Dink and his two best friends,...

Dink and his friends unearth the mysterious truth behind the envelopes incorrectly delivered to his house.

While visiting Wallis's castle, Dink and his friends investigate strange noises that lead them to a dangerous secret.

When Ruth Rose and her friends, vacationing in Florida, discover that her grandmother is about to invest in a project to recover sunken treasure, they stumble upon evidence that the entire plan may be a fraud.

While picnicking on Squaw Island, Dink, Josh, and Ruth Rose find a hundred dollar bill, and when they return to explore further they find an entire cave full of money.

Dink and his friends meet an exchange student, Sammi, who is actually the prince of an island country, hiding from those enemies who have kidnapped his parents and who may be after him as well.

Dink, Josh, and Ruth Rose help catch the thieves who have stolen the treasure from the museum's mummy exhibit.

While visiting Dink's uncle in New York City, Dink, Josh, and Ruth Rose help uncover who is responsible for stealing a very valuable painting.

When someone steals the money the town has been collecting to help the ducks, Josh and his friends try to find the thief.

At Green Lawn Elementary, the entire school becomes involved in a mystery when Mr. Bones, the skeleton in the nurse's office, disappears.