Liu arrives in Zhongnanhai and is detained by guards. He meets with President Chen and reveals that Wang’s autopsy showed mercury poisoning, not dementia, and requests access to Wang’s secret secondary office. Meanwhile, Alice, Vivien, Kai-wen, and Ming-na are on a helicopter bound for Taiwan. Haunted by the phrase “mad as a hatter” (303), Alice connects it to mercury poisoning—the origin of the phrase, as 19th-century hatmakers worked with mercury and often developed cognitive symptoms of mercury poisoning—and realizes Pangu’s headquarters must be in the tomb of the first emperor, Qin Shi Huang, which is rumored to contain rivers of mercury. She persuades Captain Hu to call her father, but Liu, who is meeting with President Chen at that moment, doesn’t answer.

In the White House, Chief Petty Officer Bahri is escorting McAllister down the stairs at gunpoint when another woman enters the stairwell, momentarily distracting Bahri. McAllister grabs Bahri’s gun and kills her, but when he turns to shoot the other woman, she shoots and kills him first.

On the helicopter, Alice convinces Hu to change course and take them to the Terracotta Warriors site in Xi’an.

A flashback introduces Auntie Gugu, Liu’s aunt and an original Pangu member whose radical faction now leads the organization. From her market stall, she confirms that Wang and McAllister are dead and believes Vivien’s group is as well. She anticipates that the final attack—a missile launch from the compromised USS Ronald Reagan in the South China Sea—will proceed as planned.

In Xi’an, Captain Hu realizes that the guards protecting the Terracotta Warriors are Pangu operatives and disarms them. Alice leads the group toward the unexcavated section of the tomb. Fearing the tomb’s curse, Captain Hu and Corporal Song abandon the group to search for a different entrance, but not before Song secretly gives Alice his pistol. The remaining four—Alice, Vivien, Kai-wen, and Ming-na—use pickaxes to break through the stone wall sealing the emperor’s tomb.

In Beijing, Liu breaks into Wang’s secret office and finds proof that Wang was siphoning money, but nothing about Pangu.

Inside the White House, President Pardington learns of the two deaths in the stairwell from his Chief of Staff, Kathleen. Realizing another traitor is in his administration and on the premises, Pardington refuses to evacuate to a secure location.

Meanwhile, Alice’s group crawls through the opening in the tomb wall and discovers a massive, artificially-lit underground city. The necropolis is filled with lifelike terracotta figures of villagers and merchants. Their awe turns to horror as they find that the city is also littered with the skeletons of the 700,000 workers who were sealed inside to die after completing the tomb. After finding the skeleton of a person killed by one of the tomb’s legendary booby traps, a shaken Vivien wants to retreat. However, the group now looks to Alice, who resolves to push forward and find Pangu.

In Beijing, President Chen takes his place on the reviewing stand for the parade, knowing he is Pangu’s target. In the tomb, the group hides from guards who show clear signs of mercury poisoning. Alice searches the body of a dead guard and finds an MSS ID and a crude map. The group deduces that Pangu would operate from the palace, not the temple, to avoid the emperor’s cursed burial site. They soon arrive at a vast field containing the palace and temple, separated from them by a wide river of mercury. Using their belts and a pickaxe, they manage to hook a single dragon-shaped boat from the opposite shore and pull it across.

Meanwhile, Liu, while in a taxi contemplating getting a coconut bun like Liam Palmer, has a realization: A person experiencing cognitive impairment, as Wang reportedly was, would not hide clues logically. He returns to Wang’s ransacked official office to search again.

The group crosses the mercury river in the boat, which contains the skeletons of two Taoist priests. They are attacked by Pangu guards at the palace dock. Kai-wen and Vivien hold off the guards, urging Alice and Ming-na to run ahead. Before fleeing, Alice gives her pistol to Vivien. After hearing gunfire, Alice and Ming-na press on, believing the others are dead. Inside, they dodge a booby trap. Ming-na notices Taoist symbols on the back of the map and realizes Pangu is located in the temple, not the palace. They head for the temple, where they hear the sound of fans used to cool computer mainframes, suggesting that they have found the heart of Pangu. They stop short when they see what appears to be a living man dressed as Emperor Qin Shi Huang sitting on a throne. Just then, guards catch them and hold them at gunpoint. Alice uses the MSS ID she took from a dead woman to convince the guards that she is their superior. She sends them away to guard the entrance to the compound.

In Beijing, Liu finds a photo in Wang’s official office of a girl holding embroidery. On the back is the word “Nüshu,” which he recognizes as the last word spoken by Wang’s dying wife.

In the temple, Alice and Ming-na find Pangu’s control center: A room full of servers and technicians. A countdown to the final attack is on all screens. She identifies an old man with a laptop as the mastermind. Ming-na creates a diversion while Alice pursues the man, who flees down a corridor until he is suddenly killed by arrows from an ancient booby trap. Alice grabs his laptop, which displays the countdown. She believes there must be a code that would allow her to stop the countdown, but she has no idea how to figure out the code.

Aboard the USS Ronald Reagan, nuclear warheads are prepared to fire, controlled by Pangu. Engineers scramble to override the launch sequence, but nothing works. The ship’s captain orders fighter jets to prepare to destroy the ship, killing everyone on board, to prevent the warheads from launching.

She finds the same photo of the girl with the embroidery in the man’s pocket. On the back of the photograph is the word “Nüshu.” Using the servers’ network, she connects her phone and discovers that Nüshu is a secret script used centuries ago in China by women, at a time when women were forbidden from learning to read and write. The embroidery the girl is holding displays the code, but it is written in a circle, and Alice doesn’t know where it starts. In a flash of insight, she realizes that Liam wrote a Nüshu symbol on the li bien ball. With seconds remaining, she hits the corresponding key.

The ICBM launch is aborted at the last second, but not soon enough to prevent the fighter jets from firing on the USS Ronald Reagan. In Beijing, the jets that President Chen expects to kill him instead fly past harmlessly. Liu, waiting and hoping for a message from Alice or Vivien, remembers the photograph of Liam on the boat. He recalls that he’s seen the pattern of dots and slashes before—not on the coconut bun held by Liam in the photo, but on the ones sold by Auntie Gugu.

Alice is found by Vivien, each overwhelmed with relief that the other is still alive. Kai-wen and Ming-na also reappear, and Ming-na knocks out the “emperor”—just a man in armor. As they escape through a hidden tunnel, Alice activates a mechanism that plunges the tomb into darkness, trapping the remaining terrorists. Captain Hu deliberately triggers a tunnel collapse to seal the exit, nearly dying before Alice and the others pull him free.

On the helicopter, Alice explains that the code to stop the launch was a single Nüshu symbol for “woman,” leading them to conclude Pangu’s true leader is female. Alice recalls admiring an embroidered Nüshu scarf worn by a woman at the White House. Meanwhile, President Pardington and Chief of Staff Kathleen Wells review intelligence. Kathleen uncovers messages from Secretary of Defense Joanne Clavelle’s files that contain clear instructions related to the Pangu attacks, proving that Clavelle is behind Pangu. The messages also contain mysterious markings that appear to be a secret code. She then points to a photo where Clavelle is wearing a scarf embroidered with the same markings.

The group meets Liu on a Hong Kong tarmac. He reveals that his Auntie Gugu is Pangu’s leader; she faked her arrest to avert suspicion. The little girl holding the embroidery in the photograph is her, and the Nüshu code is also on her bakery sign. Alice shares her suspicion about a high-level traitor in the White House. Liu contacts President Chen, who provides a secure line to President Pardington. Vivien calls Pardington, but the Situation Room is breached by security led by Secretary Clavelle. On the secure line, Alice tells Pardington that the Nüshu scarf belongs to one of his closest advisors. He hangs up and directs his head of security to arrest Joanne Clavelle.

The group confronts Auntie Gugu at her bakery. She confesses, revealing that the Nüshu names on her sign belong to her female ancestors and that the code symbol meant “woman.”

Later, in the Oval Office, Vivien and Alice meet with President Pardington. Alice identifies Kathleen Wells as the traitor, recalling her Nüshu-embroidered scarf. Pardington confirms that he knew and has Kathleen arrested. Joanne Clavelle is brought in and exonerated; Pardington explains he falsely accused Clavelle to disarm Kathleen. Over tea, Vivien and Alice recount their ordeal.

In Taipei, Ming-na presents Kai-wen with a priceless jeweled necklace from the tomb. In Washington, DC, Liu and Kevin cook for the family. Alice finds Vivien at the piano playing the lullaby from her childhood, and the two share a moment of reconciliation.