A locked trunk and a secret diary lead Mallory and the Baby-Sitters into a big mystery in this entry in the classic hit series. Mallory and Claudia are helping Stacey unpack from her move back to Stoneybrook when they find an antique trunk in the McGill’s attic. Stacey doesn’t want the dusty thing, so she gives the trunk to Mallory . . . who finds an old diary at the bottom of it. The diary belonged to Sophie, a girl who lived in Stacey’s house in the 1890s. As Mallory reads deep into Sophie’s diary, she discovers a mystery on their hands to solve, because Stacey’s house isn’t big enough for her, her mom . . . and a family of ghosts! The best friends you’ll ever have—with classic BSC covers and a letter from Ann M. Martin!

Mallory discovers an old diary in the McGill's attic written by a young girl who lived in the house in the late-nineteenth century and, in the course of reading the fascinating journal, uncovers a shocking mystery.

Stacey's parents are getting a divorce. Stacey is sad and angry, and she has a big decision to make--stay in New York with her father, or move back to Stoneybrook with her mother.

Kristy looks for a way to help a little girl with autism in this special entry in the classic hit series. Kristy’s newest baby-sitting charge is Susan Felder, who goes away to a special school. Susan isn’t like most kids. While she can play the piano and sing beautifully . . . she can’t talk to anyone. Susan is autistic. She lives locked inside her own secret world. Kristy thinks it’s unfair that Susan has to be sent off to school and is treated differently from everyone else. But Kristy’s going to try to change that—by showing everyone that Susan’s a “regular” kid, too. And then maybe Kristy’s new friend can stay in Stoneybrook for good. The best friends you’ll ever have—with classic BSC covers and a letter from Ann M. Martin!

Mary Anne and Stacey are in Sea City working as mother's helpers for the Pike family. When each of the girls meets up with her boyfriend from last summer, things start to get complicated.

The hit series is back, to charm and inspire another generation of baby-sitters! When Dawn starts getting threatening notes and odd phone calls while she's baby-sitting, she doesn't know what to do. The notes are signed "Mr. X," and they're beginning to get scary. Normally, she'd tell the rest of the BSC, but this time things are different.The kids at Stoneybrook Elementary are having a Sitter of the Month Contest. The Sitter of the Month has to be someone who is in control--someone whose jobs always go smoothly. Dawn doesn't want to blow her chances at winning. But what if she's in real danger?The best friends you'll ever have are detectives, too!

In a breakthrough book for the series, Mallory says good-bye to Stoneybrook and hello to the Riverbend School. The boarding school in the Berkshires introduces Mallory to a new group of friends--and a not-so-friendly roommate.