Mary-Kate and Ashley work as matchmakers to get Mrs. Baker and Mr. Fillmore together so that Carrie, a student of Kevin, will be hired as their new baby-sitter.

After Kevin buys a new telescope, Mary-Kate and Ashley snoop into other people's business. They think they witness their neighbor, kindly old Mrs. Baker, murdering her elderly boyfriend, Mr. Fillmore. The situation gets even scarier for the twins when Kevin asks Mrs. Baker to take care of them so he can attend a jazz concert with Carrie. Meanwhile, Carrie hears Kevin play the saxophone and encourages him to perform for audiences as he used to.