It's the seventh day after the kidnapping, and the FBI has told the media they're closing in on the kidnapper's location. In interrogation, student Emma Vries tells Dunn and Finley about the firefight, when Kyle shot Hurst to protect Gibson. Emma identifies the CIA's Thayer as the primary attacker; Widener must have gotten him into the mansion somehow. Still, it doesn't seem like the CIA knows the mansion's location. Regardless, Olsen wants his team to deliver this news to President Devore. Confirming that his son Kyle killed Hurst, Devore asks Olsen for the truth. Dunn reveals their unproven belief that Gibson is the kidnapper and his involvement with the CIA death squad. Olsen claims Widener has been stonewalling, so Devore summons him. Devore wants to know more about the video Congressman Wirth uploaded to his phone before he died. Does it contain proof of a CIA death squad or not? As predicted, Widener stonewalls, claiming they don't think Gibson has anything to do with the kidnapping. When an angry Dunn accuses Widener of orchestrating her and Meg's kidnapping yesterday, he denies it, and Olsen tells her to step out of the room.
Back at the mansion, a jittery Ian has discovered a damaged panel in the bathroom, which offers direct access to Gibson's kitchen command center. When Gibson learns the National Guard is six hours away from discerning his location, he decides to buy himself 12 hours and calls Jin Liao's parents, Meng and Sya, who is a colonel in China's intelligence service. Meng is stunned to discover his wife also works for the Chinese government, but becomes a believer when she scans her palm to open a secret safe. Grabbing her laptop, Sya heads out to an apartment in a luxury senior apartment to upload a ton of code. Jonas is finally delivered to the mansion, where Gibson promises to save his life - but only if Jonas will help him take out Widener. Then Gibson tells Beth Ann and Kyle he's going to need them to organize the other kids to help keep track of the guards, who have changed their schedule since the attack. The kidnappers' plan is falling apart, and they need to get out of the mansion as soon as they can.
Suddenly the FBI offices are thrown into darkness - their entire network has gone down. But it's not just the FBI - anything connected to the Internet seems to have gone down, including banking systems and emergency services. Both Olsen and Widener concur they need to go to INFOCON 2; Finley tells Dunn this means they're under attack and shutting down the country before someone else does. Since the President is in the FBI building, it will become "the castle" for the duration of the cyber attack, i.e. the last position to fall. Widener informs the President that the code is a variant on a known Chinese military virus; this could be an act of war. Dunn and Finley think it's all a Gibson smoke screen. Now all the teams that were closing in on him are being pulled away. The cyber attack is likely the work of a Ballard parent, and they know Meng Liao is cultural attachÃ© for the Chinese embassy. Devore orders Finley to get to the bottom of it... so they break into the Liao residence. The partners quickly disarm Meng, who has no idea where his wife is. Finally, his mother pipes up. Her son is weak, and he doesn't know war like she does. Sya left with her laptop and the key to grandma's apartment in the senior home.
Gibson leads Jason to a lab he's set up in the mansion to make more "chemical supplement" - whatever it was given to the death squad soldiers. Jonas balks, but Gibson assures the next step is to free those soldiers; but without the supplement, they're of no use. It's the only way to destroy Widener. Meanwhile, Jin Liao is ecstatic since the kidnappers took his proof-of-life photo. Beth Ann wants him to help Gibson and the kids break out, but Jin insists the Chinese only let his mother have one child and it's him. He has to get out. Sadly, Sya is recording a goodbye message, full well knowing she'll never see her son again. She's only doing what she needs to do to save his life. After sealing her cell phone into an envelope and mailing it to Jin, Sya makes contact with a Chinese agent. Central Command has activated them, and the agent is to make sure the Americans can't find her.
Dunn and Finley are casing Meng's mother's deserted apartment, finding only Sya's laptop doused in acid. Just then, the Chinese agent starts shooting, so Finley returns fire. The chase ends when the agent slumps in a stairwell, bleeding out. With no phones, Dunn and Finley decide to drive the agent to the hospital, since he's the only line they have on Sya. Meanwhile, the Joint Chiefs have advised Devore that if they don't strike now, they'll lose the ability to do so. Widener wants to call Putin, which is when Dunn calls Devore to report the cyber attack tracks to Sya - it's not an act of war. Knowing they won't be able to find her without help from the Chinese, Olsen appeals to Devore. Why not trade America's best asset in Beijing for the information? Though Widener promises he'll have the cyber attack licked any minute now and he's spent decades putting his asset in place in China, the deal gets done. Olsen calls Dunn with the location of a Chinese government safe house, a church.
As traumas and emergencies mount across the eastern seaboard, Chinese agents start firing on Dunn and Finley at the church. It's not long before they find Sya holed up in an office. She takes responsibility for the cyber attack, knowing she'll be executed for her actions. Refusing to reverse the attack, Sya claims she has been trained to withstand torture, so Dunn and Finley take her to the hospital to view the river of trauma victims. Gibson has asked Sya to make war to save her son; Dunn and Finley are asking her to end a possible war to save many sons. When the power comes on at the mansion, Gibson is angry Jonas will be unable to complete his work. With the most important parent mission still to come, Gibson insists this parent must know the price of failure. Unaware Ian is watching through the bathroom wall, Gibson shoots Jin saying, "They made me do it."
With the power grid back online, the search for the mansion is back on too, and the FBI returns to normal operations. Finley informs President Devore that Abby Hurst has come to see him, and that he doesn't believe Al Hurst had anything to do with the kidnapping. The President agrees, but now he has to tell Abby that his son shot her husband. The President leaves to do damage control just as the purloined CIA video is posted to every news outlet in the universe. Gibson calls Widener to warn that he's coming to destroy his life...