After Jess discovers her late mother’s involvement in the treasure hunt, Jess becomes even more determined to unravel the secrets her mother never told her about their past. She enlists the help of her friends and Liam. This newly formed team of treasure hunters bonds as they decipher a clue handed down by the Masons and embark on a risky mission that sends them to a mansion once owned by and American icon.

Trust no one on a treasure hunt. Jess begins to wonder if this is true as she suspects someone close to her might’ve leaked an important clue to Billie, but she doesn’t want to believe it. While Tasha uses her tech skills to ferret out the mole, Jess realizes the key to the next step in the treasure hunt is locked in the Rare Books Room at the Governor’s mansion, leading Jess and her friends to plot a caper during the Governor’s Ball, where Jess’s trust in her friends will be tested.

Not knowing who’s good and who’s bad, Jess works with Billie and deciphers a hundreds-year-old clue that points to a famous 18th century landmark, and together they plan an impossible heist during an historic reenactment to retrieve the next piece of the treasure map. But things don’t go as planned, and Jess is ultimately faced with the most difficult decision of her life.

After getting captured by Billie, all hope of saving the treasure seems lost for Jess. Tasha, Oren, Ethan, and Liam try to track Jess down using Tasha's tech skills. Meanwhile, Liam finds a hidden cypher left behind by his grandpa, which holds the truth about Billie and the mysterious Salazar.

With his identity finally revealed, Salazar joins Billie in the final leg of the treasure hunt, where Jess and her allies try to outwit Billie using Jess’s knowledge of puzzles and history to escape and protect the treasure.