DAN BROWN'S THE LOST SYMBOL

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, Langdon follows the next clue while Katherine joins Sato to find her father.

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.

Mal'akh sheds light on Zach's final days in prison. Langdon and Katherine face their shared past.

Katherine and Langdon persuade Isabel to protect herself. Peter reconnects with Leviathan members.

Langdon, Katherine, Nuñez and Peter partner with Sato and the CIA to spring a trap for Mal'akh.

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