The episode begins with an overview of the past year about a man (Cole) who traveled through time to stop the plague caused by the Army of the Twelve Monkeys. Joined by a woman (Cassie), they sought to save the world only to be stopped by the man considered to be his brother (Ramse). However, while fate stated that this enemy would die, the man changed history by rescuing his friend and saving the woman by transporting her to the future. With the two now separated by decades, there is nothing they can do.
In Budapest 2016, a recovered Ramse is being chased be vehicles before they trap him on a bridge. Men then approach him at gunpoint led by Olivia who has finally tracked him down. According to her, it is stated that Ramse must die after he has served his purpose, so the army now seeks to kill him to maintain the line. Ramse, however, has other plans as Cole secretly detonates the vehicles and take down the men to save his friend. He turns a gun at Olivia to demand the virus, but additional men arrive on motorcycles to fight off the time travelers since the Witness has spoken of Ramse’s death. Desperately, Cole and Ramse jump off the bridge into a river to escape.
After they escape, Olivia orders the men to protect the virus since Jennifer Goines is watching over it at the moment. One of the guards protests since that was not ordered by the Witness, but Olivia persists. Meanwhile, Cole and Ramse sneak back to their secret hideaway. Thanks to Jones’ injections from time travel, Ramse is able to heal faster and age slower, though Cole still maintains that he’s an old man. Ramse fears that since the Witness knows the future, they will always be on the run from a person who is one step ahead. Cole maintains that since he has no idea is Cassie made it to the future, it is up to him to stop the virus. Ramse argues against him since that will still mean the loss of his son. Cole lashes out at his friend, saying that if Ramse is against Cole’s plan it might be easier if they just kill each other. Instead, he offers that they split up to make it harder for the army to track them. Unfortunately, they cannot hide forever, since they were already tracked after three months. When Cole points out that they weren’t tracked in Berlin, the two deduce that they somehow placed a tracker inside of Ramse to find them. The two then plan to find a way to remove the tracker before going their separate ways. For what it was worth, Ramse assures his friend that he believes Cassie made it to the future.
In 2043, Cassie wakes up after being unconscious for four days. Jones had managed to remove the bullet albeit rather crudely. She informs Jones that Ramse was responsible for advising the army though Cole refused to shoot his friend. Cassie admits that she shot Ramse and, despite being a doctor herself, felt no difficulty in doing so. She asks about the men outside whom Jones refers to as The Messengers, similar members of the army, who now want their machine. Jones then injects herself with her formula to prevent time from altering her before the women are interrupted by Deacon who brings them to the Messengers.
Jones: Grieving over who we were only gets in the way of who we need to be.
The Messengers begin to send their own subject through the machine with an old bone with the help of Jones. She advises against it, but the group is adamant on completing their mission. As seen before in Jones’s tests, the machine obliterates the subject. The group finds that Jones had encrypted the terminal to only partially splinter the subjects without her hand. The Messengers then threaten Cassie to force her to comply, but Jones reminds them that the entire system was created based on a recorded message Cassie has yet to send. Without her, there is no time travel. The Messenger then states that whatever is meant to be will be and prepares to demonstrate by killing Cassie. Suddenly, a man is able to unlock the encryption, sparing Cassie’s life for now. The Messengers then plan to send another subject through the machine. This one leaves successfully.
Back in Budapest 2016, Cole meets up with a professor Dr. Kalman who previously worked with the army but had rejected the work of global destruction thanks to Ramse. Cole then informs the doctor on the tracking device inside of Ramse and asks for his help in removing it. The doctor at first refuses to work with them, but Cole states that they have a duty to the people who make their lives better, like he had owed to Cassie who saved his life and made him better.
In 2043, Deacon takes Cassie away, revealing that his connection to the army is necessary. Cassie quickly notices the discoloration of his skin and deduces that he has Wilson’s disease. If untreated, he will certainly die and that’s only if his men don’t notice. Cassie offers to return to her time to retrieve the medicine needed for him as long as he helps her escape. Deacon refuses to listen to Cassie although she further states that the army was responsible for the destruction of the world if he continues to help them.
In 2016, Dr. Kalman detects the tracking device and, despite the conditions, proceeds to help remove it from Ramse. He only requests that Cole move out of the room as the sight of a gun makes his hands shake. With some difficulty, he removes the tracker but manages to paralyze Ramse with the medicine. At this moment, the doctor delivers a message that the plague is set to begin in a matter of days on the Chinese New Year, on the year of the monkey thanks to Jennifer Goines. By delivering the message, the doctor seeks protection from the virus in exchange for killing Cole. Cole, however, gets the jump on the doctor and is forced to shoot the man.
In 2043, Deacon confronts Cassie on helping him. Unfortunately, her only option is for her to kill her guard for them to escape. The two snatch weapons from the body and then release the rest of West 7 as well as a few soldiers including Marcus Whitley to help take back the base.
Back in Budapest, Cole apologizes for the loss of Ramse’s son but plans to take his own path to stop the virus. Ramse then reveals that Jennifer Goines has the virus in New York since he believes that Cole will stop at nothing anyway and probably die. This time, it will happen under his friend’s watch. The two then head to New York.
Deacon: Believe me when I say Do No Harm died 30 years ago.
At New York, Jennifer Goines walks the streets and wanders into a speed-dating session. To her unsuspecting partner, she reveals a vial of the virus that will be used to kill the world. While he is understandably frightened at her apocalyptic rantings, she then offers him a chance to save the world by shooting her now with a gun she carries. When he refuses, she leaves once the timer goes off to switch dates. The man then calls 911.
In 2043, the West 7 plan to quickly storm the base as the Messengers keep sending more subjects to the past. Unfortunately, they’ve sealed off the lab. Marcus and Deacon then figure that through the power system outside the lab, they could, in theory, overload the machine causing a reaction that would take out everyone in the room. The two work to overload the machine while Cassie warns Jones to get down. The group successfully overload the machine, but the final Messenger makes one final move to kill Jones. He’s then shot by Deacon as Marcus and Cassie helps Jones. Jones reveals that the Messengers sent back six subjects, but it could take months before they can recreate the machine. Either way, the mission will continue.
Back in New York, Cole and Ramse search for Jennifer in the middle of a Chinese New Year celebration. The two then split up to find the woman and stop her from releasing the virus. Cole finally spots Jennifer staring at an image of a monkey, and the two give chase through crowds and up a building. She finally stops and reveals the virus when Cole points a gun at her. She’s relieved to see someone try to stop her and orders her to kill him. Cole refuses to kill Jennifer and instead asks for the vial. Suddenly, additional guards with guns from the army arrive, stating that the Witness has spoken for her to fulfill her purpose. In the meantime, Ramse is knocked out in an alley.
Cole tries to convince Jennifer to make a choice, but the guard states that this is only coming from a man who tried to change fate before by rescuing Ramse. In the end, fate will occur. At that instant, all of the guards are shot down by a surprise appearance from a returning Cassie. She then reveals that she was sent from 2044 after spending eight months in the future. From tracking down a police report from the 911 call, Jones and Cassie were able to track the virus to Jennifer. Cassie orders Cole to move in order to kill Jennifer to stop the virus. Cole then turns his own gun on her, refusing to let her kill Jennifer.