Langdon travels to the Klementinum Library, where the Codex Gigas is on display, hoping to meet Katherine. He is spotted by a transit worker, who recognizes his face from Pavel’s alert.

Faukman arrives at Random House, closely tailed by Auger and Chinburg. Because Faukman tossed his phone while fleeing, the agents are forced to follow him into the building to find out what Alex Conan has learned about the hack.

Ambassador Nagel learns of the UZSI alert on Langdon and alerts Finch, who furiously decides to come to Prague. Finch orders Agent Housemore to secure the Gessner’s lab. Meanwhile, the Golem prepares to infiltrate Threshold.

Langdon recalls a conversation in which Solomon argued that artistic depictions of halos represented beams of consciousness flowing in to human brains, rather than out of them. For Solomon, this reversal supports her arguments about nonlocal consciousness.

Langdon enters the Klementinum Library and is surprised to find it opened at the same time Katherine sent her email. He is followed by Pavel, who has received a number of tips about his location following the alert.

Auger and Chinburg overpower a security guard and follow Faukman into Random House. Faukman meets with Alex Conan, who reveals that he mistakenly thought Langdon was dead because of his lost phone signal. As Conan is about to reveal the identity of the hackers, Faukman realizes they are not alone.

Langdon spots Pavel inside the Klementinum Library and realizes he is in danger. He attempts to open a hidden passage in a book case that he showed Solomon the day prior, but it is locked. He realizes Katherine is inside, and she lets him in.

Solomon explains that she hid in the museum after receiving a frantic call from Conan about the hack and his suspicions about Langdon’s death. Pavel realizes where Langdon is hiding and orders museum staff to leave the room and not re-enter for any reason.

As the heavily armed Golem approaches Prague’s Old-New Synagogue, he recalls the moment shortly after his arrival in Prague when he first heard the legend of the golem. He believed that he was a reincarnation of the golem brought to Prague to protect Vesna.

Pavel shoots into the locked hidden staircase, with no response. He decides to push the heavy display containing the Codex Gigas against the wall to climb onto the balcony and attack from above. As he works, Langdon notices a possible tool for escape on the ceiling.

Housemore finds the Gessner Institute empty. In New York, Faukman misleads the eavesdropping Auger and Chinburg into believing he thinks the hacker was an online publisher. As the agents are leaving, they are intercepted by Random House security and detained by police.

As Pavel gets closer to the balcony, Langdon uses a phone charger in Solomon’s purse to start a fire with the sole remaining copy of her manuscript. Solomon panics, but Langdon insists the manuscript would be confiscated as soon as they left the museum anyway. Solomon’s trust in Langdon wavers.

Museum staff ignore Pavel climbing onto the balcony as they attempt to stop the fire. As Pavel is about to descend the hidden staircase, Daněk appears with Marines to detain him. Daněk persuades Langdon to exit the staircase. She is shocked to see Solomon with him.

Daněk refuses to let Langdon or Solomon contact anyone until they talk to the ambassador. She receives orders from the Ambassador to look for Harris at Vesna’s apartment. An embassy limo takes Langdon and Solomon to the ambassador’s house, where Langdon knows they have no specific rights as US citizens. He realizes the flowers from the ambassador in their hotel room were bugged.

The Golem enters the Old Jewish Cemetery, a three-acre space where over 100,000 bodies are buried. He kneels at the grave of Rabbi Loew, the real-life 16th-century Jewish mystic who is credited with creating Prague’s golem. The Golem feels the spirit of his namesake enter him.

Solomon compares consciousness to quantum physics, which is defined by its unpredictability. She argues that it is difficult to repeat experiments proving nonlocal consciousness because consciousness exists on the quantum realm, which reacts to observation. However, she claims to have conducted repeatable experiments.

Solomon explains that the brain is able to filter extraneous information—like ambient noise at a party—through a chemical known as GABA. Solomon compares GABA to a filter preventing the brain from accessing the full spectrum of consciousness. She connected with Brigita Gessner when Gessner published a study about a neural chip that triggered the brain’s natural GABA response to stop seizures.

Solomon’s research shows that GABA levels drop during death and after use of psychedelic drugs, suggesting that the brain’s filters also drop during these moments, allowing a person to experience the universal consciousness more fully. As they near the ambassador’s residence, Langdon worries they are entering a trap.

Langdon warns Solomon that the ambassador’s residence might be bugged and begins to worry that she shared too much of her research in the limo. Ambassador Nagel greets the pair with an apology.

In a private room, Nagel explains that she was ordered to bug the hotel room by Mr. Finch, who is coming to speak to Langdon and Solomon, and who believes that Solomon’s book is a risk to national security. Nagel asks Langdon and Solomon to sign an NDA, but they refuse. Nagel suddenly receives bad news and leaves.

Langdon calls Faukman, who reveals that Solomon’s manuscript was hacked by In-Q-Tel, a venture capital firm investing in advanced technologies. The firm is funded by the CIA. Realizing that Nagel left the CIA to become ambassador, Faukman urges Langdon and Solomon to flee.

Nagel is devastated to learn of Harris’s death from Daněk. She became ambassador after Finch planted evidence in her apartment leading to her dismissal from the CIA. Nagel feels like a pawn being played by the old boys’ club of the federal government. She decides to stop cooperating.

The Golem enters Gessner’s lab to retrieve a tool needed to destroy Threshold. He is briefly spotted by Agent Housemore, who has been ordered not to let anyone into the lab. He overpowers her before she is able to react. As he kills her, he tells her his name.

Nagel lies to Finch, claiming that Langdon and Solomon signed the NDAs. She then confirms to the pair what Faukman said about Q and the CIA, explaining that Finch believes Solomon’s research poses a threat to Q’s most important investment: Project Threshold, housed in the middle of Prague.

Nagel reveals that Project Threshold is housed in the Folimanka bomb shelters, which the US Army Corps of Engineers helped to build. She suggests that Langdon and Solomon give a letter sharing what they know to a lawyer to release if they die suspiciously in the hopes that the CIA will not come after them. Langdon refuses, calling it blackmail.

Flashbacks reveal that Gessner was sent by Finch to obtain a copy of Solomon’s manuscript when Finch learned it was being held in a secure server. After their first meeting, Gessner sent Finch a text claiming Solomon lied to her, but never followed up. It is revealed that Gessner’s key to Threshold is biometric, meaning it will not work if stolen.