When Dink, Josh, and Ruth Rose visit a dude ranch in Montana, they find themselves with another mystery to solve, this one involving the theft of money from the ranch's safe and of a large gold nugget that Josh had found.

An art thief is on the loose! Dink, Josh, and Ruth Rose are visiting Dink's Uncle Warren in New York City when several paintings are stolen from his apartment building. A trail of orange peels, a missing pie, and an orange hair are the only signs that someone was there. Do the kids have enough clues to catch this crafty and hungry crook?

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

Third-grader Dink and his detective friends hope to receive a big reward by finding the person whose video recorder picked up a picture of the local bank robber.

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

Dink, Josh, and Ruth Rose investigate the disappearance of a valuable racehorse that Dink's uncle and his friend, Forest Evans, have just bought and entered in a race at Saratoga.

Dink Duncan and his two friends investigate the apparent kidnapping of famous mystery author Wallis Wallace.

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.

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.

Reports of zombies and grave-robbers alarm the people of a Louisiana swampland village, but Ruth Rose, Josh, and Dink begin to suspect that the supernatural may not be the cause of the eerie occurrences.