The fourth floor twins

Two sets of twins receive a message in a fortune cookie, warning them to beware of a man in a blue hat.

Two sets of twins suspect their neighbors of wrong-doing when they observe the strange behavior of the couple's nephew.

Two sets of twins catch a thief while tracking down a missing suitcase in a train station.

When a famous sculpture is stolen from the museum, two sets of twins team up to track down the thief.

Two sets of twins receive a message in a fortune cookie that warns them to beware of a man in a blue hat.

Two sets of twins launch a wild chase when the "disappearing parrot" in their school talent show magic act really does disappear.

Two sets of twins receive a message in a fortune cookie, warning them to beware of a man in a blue hat.

In an extraordinary day at the beach, after winning a sand castle contest, two sets of twins resolve the mystery of the disappearance of a rich woman's dog.