Young professor Robert Langdon is pulled into a complex mystery when his beloved mentor, Peter Solomon, is kidnapped; armed with knowledge of history and symbols, Langdon must work together with Peter's daughter and other allies to save him.

Reeling from the day's events, Robert and Katherine get help and shelter from an old friend while trying to decipher the most recent clue; amid visions of his past, Peter attempts an escape.

With the CIA hot on their trail and Mal'akh demanding they split up, Robert and Katherine turn to Nuñez for help; Sato interrogates Bellamy and is pressured by her superiors to produce answers for the growing number of questions regarding the case.

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

When Mal'akh sends a disturbing video of Peter, Langdon has no other choice but to reunite with Katherine and team up with Sato for a bold move; Nuñez follows a hunch.

Mal'akh pressures Langdon and Peter to decipher the clues; Katherine, Nuñez and Sato try to pick up the pieces after the failed drop.