[1] The story picks up two years after the original series The 39 Clues and is about the Cahills' attempt to save members of their family that have been kidnapped by following the instructions given by Vesper One.

At 8:42 EST, across various time zones, Fiske Cahill, Reagan Holt, Natalie Kabra, Nellie Gomez, Alistair Oh, Ted Starling, and Phoenix Wizard are kidnapped.

Amy addresses the Cahill family via her command center, promising to stop the Vesper while keeping the hostages alive.

She calls for Ian Kabra and Sinead Starling to watch the Command Center, while Hamilton Holt and Jonah Wizard meet her in Italy.

While Dan questions how the Vespers so quickly identified the museum's painting as a fake, Amy contacts Attleboro, tasking them with finding a charger for the phone.

Dan and Amy meet Atticus and his older brother, Jake, at the Colosseum and find the original copy of Il Milione.

The siblings make the drop, only to find that Vesper One will not release the hostages unless Dan and Amy do another task in Lucerne.