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!