When twelve-year-old Lara Finkel starts her very own detective agency, FIASCCO (Finkel Investigation Agency Solving Consequential Crimes Only), she does not want her sister, Caroline, involved. But Caroline won't give up, and when she brings Lara the firm's first mystery, Lara relents. But Lara and Caroline's truce doesn't last for long. Caroline is busily texting a new friend. Lara can't figure out what they are up to, but it can't be good. And Caroline doesn't like Lara's snooping - she's supposed to be solving other people's crimes, not spying on Caroline! As FIASCCO and the Finkel family mysteries spin out of control, can Caroline and Lara be friends again?