Young professor Robert Langdon is pulled into a complex mystery when his mentor is kidnapped.

Robert and Katherine get help from an old friend while trying to decipher the most recent clue.

With the CIA on their trail, Robert and Katherine turn to Nuñez for help; Sato interrogates Bellamy.

Forced to split up by Mal'akh, Langdon follows the next clue. Katherine teams up with Sato to find her father another way.

Langdon must reunite with Katherine and team up with Sato while Nuñez follows a hunch.

Mal'akh pressures Langdon and Peter to decipher the clues. Katherine, Nuñez and Sato try to regroup.

Cornered Mal'akh sheds light on Zach's final days in prison; after reuniting, Langdon and Katherine face their shared past and the ripple effect that Zach's fate had on it.

Fearing Katherine's mother might be in danger, Katherine and Langdon try to persuade Isabel to protect herself; Peter reconnects with his fellow Leviathan members after Mal'akh turns his wrath on the organization.

Finding an unexpected clue, Langdon, Katherine, Nuñez and Peter partner with Sato and her CIA colleagues to spring a trap for Mal'akh; as the night unfolds, the real puzzle is quickly discovered.

As Mal'akh's plan culminates, Peter and Langdon wrestle over the sacrifice needed to save Katherine.