Wells and Jane are researching World War I on the Internet to try to figure out why Stevenson would use the time machine to travel to Paris, March 30, 1918. Wells remembers that Stevenson met an Englishwoman, Pauline Ayers, in Paris when he was in medical school in Paris in 1890. Jane looks Ayers up and discovers that she had had a son in 1891 and the father on the birth certificate is named as John Stevenson. Henry Ayers was apparently killed in action on the date that Stevenson traveled back to. Wells and Jane believe he has gone back to save his son's life. Vanessa provides period authentic clothing and finds currency they can take back to 1918 with them.
In Paris, 1918, Stevenson has killed and stolen the clothing and money of a passerby.
In the present, Vanessa has not been able to uncover anything about Project Utopia but plans on meeting with a colleague of her father's. Wells, meanwhile, refuses to let Jane join him on this trip. Vanessa provides him with a gun for protection which he doesn't want but takes anyway.
Stevenson orders a glass of wine at a cafe where the army doctors often hang out, looking for Henry Ayers (Cameron Cuffe). Turns out the cafe owner he is talking to, Margot (Leslie Fray), is engaged to Henry who walks in just then. Stevenson tells him that he knew his mother and they sit down and talk about her, the war, and the nature of killing and doctoring. Stevenson starts to realize that his son is a true doctor with no hint of his psychopathic tendencies. Wells walks in just in time for the next round of drinks. Wells and Stevenson argue over the nature of war as Wells tries to convince Stevenson that he cannot interfere to prevent his son's death.
In the present, Brooke is tending to Griffin's injuries. They discuss why Stevenson would go to look for his son. Brooke uses some experimental skin tissue to repair Griffin's knife wound. He recognizes it as their father's research and asks to see what else she has been up to in her lab. She introduces him to Nick, the berserker who beat Stevenson up previously, who demonstrates that he has the strength of six men in a completely relaxed state through an enhancement drug that Brooke developed. Griffin is concerned about the legality of Brooke's experiments and whether Vanessa will find out about their connection to Project Utopia. Brooke points out that Vanessa's family destroyed theirs and Griffin needs to focus on that.
Griffin finds Jane going through archived photographs from Paris on March 30, 1918. Griffin volunteers that he wouldn't have taken her with him either if he were Wells, stating that no one wants to put someone they love in danger. Jane is bothered by what she sees as chauvinistic attitudes but feels better at the idea that Wells "loves" her. Griffin also plants the seed of the idea that Wells will have to return to his own time eventually which makes her sad.
Wells and Stevenson argue over drinks in Paris. Wells tries to convince Stevenson that he cannot interfere with his son's death.Stevenson has decided to interfere in Ayers' death in some way other than convincing him to desert his men. Wells tries to force him to abandon his plan by holding the gun on him but Margot pulls her own weapon on him, forcing him to let Stevenson go. Wells tells Margot she needs to stop Stevenson because he's going to grab Ayers. She sends a soldier to get the British commander.Vanessa is meeting with Dr. Cedric Myers and he doesn't want to talk about Project Utopia. When Vanessa presses him, he admits that her father probably stole the research that the company used to create medicines that saved the company from bankruptcy. He promises to look at his files from when he retired. When she returns home and is greeted by Griffin, Dr. Myers calls and lets her know he has found something. She rushes over but Griffin overhears and contacts Brooke to let her know that they need to track down Myers immediately. Brooke sends Nick who kills Myers with an electrical shock administered between his fingers. Vanessa arrives before he can leave. She finds the Project Utopia file but is distracted by finding Myers' body. Stevenson lures Ayers away from his men by saying he has information from the father that Ayers believes abandoned his mother. Alone, he warns Ayers that his men will be ambushed and killed. Ayers doesn't believe him and storms away. Stevenson grabs him from behind and drags him back into the supply building. When Ayers regains consciousness tied to a chair, Stevenson reveals that he is his father and that despite his evil deeds, Ayers is the one redeeming thing his life has produced. He releases Ayers who runs out of the building to find out that his battalion has been attacked. He curses Stevenson and tells him to stay away from him and Margot.
Jane finds a photograph of Ayers holding Margot in the rubble of her cafe and realizes that Wells is looking in the wrong place for Ayers. She demands that Martin send her back to Paris. Martin finds an article about the cafe bombing but tries to convince her not to go. She notices in the article's photograph that one of the bodies is Wells and convinces Martin he has to send her back to save him. She arrives at the camp, asking for directions to the cafe. Stevenson intercepts her and takes the news article she brought. They rush to the cafe where Wells is being interrogated by the British army. Ayers appears just as the cafe is bombed. Everyone survives but Ayers rushes into the burning cafe when he realizes there are people trapped inside. Stevenson tries to stop him but he won't be deterred. The building collapses, killing Ayers with everyone else. Wells has lost consciousness again and Jane convinces Stevenson to help get him back to the time machine.
Back in the present, Wells gets the medical attention he needs. Vanessa's security put Stevenson in the basement for holding. Griffin confronts Brooke about killing Myers and also lets her know that both Wells and Stevenson are at the Anders mansion. He also reveals that Vanessa has Myers' computer. Brooke warns that if Vanessa finds anything, they're both screwed. Vanessa also has the Utopia file and discovers analytical data on John Stevenson in the file dated March 5, 1980.