When Dawn starts getting threatening notes and add phone calls while she's babysitting, she doesn't know what to do. The notes are signed "Mr. X," and they're beginning to get scary. Normally, she would tell the other Baby-sitters, but this time is different.

While Mallory is baby-sitting she finds a cat in the Craine's attic and names him Ghost Cat.

Claudia's room has been ransacked, and her sister Janine is acting strange. It's up to the Baby-sitters to solve the mystery.

Even without the Baby-Sitters Club to help, Dawn decides to investigate the disappearance of Thrash, the most radical surfer around and the appearance of his ghost.

Kristy and the Krashers are spending the night in a spooky old house!

Dawn and her friends try to help the police catch a robber so that trick-or-treating will not be called off.