On this week's episode, Mark races against the clock to save Demetri.
First, the main title features a teaser of Mark Bedford running frantically down a corridor lined with pipes.
We open with Demetri in a room, staring down the barrel of a gun, with the laser sight pointed square at his chest. He is strapped to a chair, lined with wires, all connected to the gun. Behind him is a giant map of lines and dashes, pointing in different directions to different dates and people, with some lines connecting back to others. Paths branch off everywhere. We see a photo of Demetri, which reads "March 15, 2010 - Demetri Dies" The date is then shown as March 15, 2010.
Cut to the bureau where Charlie is being questioned by Mark and Janis about the man who approached her at the carnival. This man, of course, is Dyson Frost. Charlie sees flashes of what he looks like, but can't be specific. Stanford suggests Charlie close her eyes since it could help her remember more. She remembers that Frost knew her name, but she didn't know who he was. In her flashback, Frost tells Charlie he works with her father, and talks to her about several Dr. Seuss stories, specifically his favorite, "1 fish 2 fish red fish blue fish." Frost tells her to do something for him, and hands her a photo to give to her father.
Mark looks at the photo, a print of two men on rocks. He reads the back. It says if they want Demetri back alive, to be at the main concourse of Union Station at noon on March 15, 2010.
Mark tells Olivia he is concerned about Charlie, but Olivia says she's fine. She doesn't want Charlie to talk to a child psychologist. Olivia blames Mark for Charlie's instability, saying she doesn't need to keep thinking her father is going to die, and have scary men ask her to deliver messages to him.
At county jail, Zoe checks in to see Alda Herzog and reminds Alda that it's the day Demetri is supposed to die. Alda dismisses it, but Zoe presses her for information. She reminds Alda that cooperation is the only way she'll get out of jail. Alda says she'll talk if she gets a hearing. Zoe says she's applied for one, but Alda presses her to get a hearing sooner, and is adamant about being in a court, today.
At the F.B.I., Mark and the team prepare for their mission to Union Station. They look at the photo Frost left: Oedipus and the Sphinx by Jean-Auguste-Dominique Ingres.
Mark says that while Frost is crazy, he is still deliberate. Mark deduces that Frost's choices may reflect his opinion on a self fulfilling prophecy, that is, Frost's inability to escape his fate. Mark relates Frost to Oedipus in that what Oedipus did to avoid his predicted fate is what actually brought about his downfall. The agents wonder if by trying to rescue Demetri, they are actually setting in motion the events which will kill him. Mark doesn't know the answer, but knows he promised Demetri he wouldn't die.
Six months before the blackout, Alda is being lead by a man outside warehouses on a dock. Inside the warehouse, the entire floor is covered with dominos. The man Hellinger introduces Alda to Dyson Frost, who is announced as one of the few remaining experiment members alive, and as the man who pioneered the initial experiments at Raven River. Frost discusses the plans for the global blackout, and shows them the first QED, the ring which kept Simon conscious during the blackout, and likely the QED Lloyd is trying to remember the formula for. Frost makes it clear to Alda and Hellinger that he will always be six steps ahead of them.
Back to present day, Demetri tries to move, but Frost enters the room, telling him if he moves from his chair, the gun will fire because its pressure sensitive. Frost explains that the map behind him is the episode's titular "garden of forking paths." All the lines represent decisions Frost made at major points in life, and the subsequent futures that resulted from them. He says it all started in the '80s with the experiments at Raven River. They engineered hundreds, maybe thousands, of blackouts, jumping 20 minutes to 20 years in the future. Every time they jumped, they saw a different possible future. Frost gives an example, that if they failed the day of the blackout, a different path would have opened. But they didn't and this brings them to today. Frost admits the future is not set in stone. He then drops a bombshell — March 15 is not just the day of Demetri's murder, it is the day of Frost's murder as well. Frost says in 78 percent of the futures, Demetri kills him. Frost says once the future has been glimpsed, it wants to happen, and they need to do something extreme to stop it. Frost says instead of killing Demetri, he wants to conform to the future as close as possible, with the death trap, accounting for the possibility they still may live. This is why he hasn't killed Demetri yet. Frost considers himself an oracle, admitting most are insane. Frost says he wants to come in from the cold. He tells Demetri that he does not know what will happen, but one of them will likely die today.
At the hospital, Bryce commends Olivia on her work. They finish up on a surgery. Olivia is interested in older anaesthesia and asks Bryce about it. She says that the older formula is something Lloyd told her may be responsible for the blackout. Bryce doesn't look happy with Olivia for talking to Lloyd.
At the hospital, Olivia is questioned by an agent about Mark's gun. He wants to know about the homeless man found shot by Frost. The homeless man's phone had a text on it from October, to Olivia, specifically the text that told Olivia that Mark was drinking in his flash-forward. The agent wants Olivia to come to the morgue to identify the homeless man's body, in case she knows him.
At Union station, Janis and a team of agents are monitoring Mark from a control van. Mark is approached by a young boy who hands him a backpack, which has a ringing cell phone. Mark gets a call from Frost, who tells him not to talk. Inside the backpack is a photo of Demetri in the chair. Frost says he'll tell Mark where and when the next blackout will occur, but he is afraid for his life since he left his associates. He gives Mark a code word to throw off his associates, and gives Mark information on where to come find him for a face-to-face. There is a number on the photo of Demetri that reads 423, which is how long Demetri has to live.
Mark takes off, through the station, following Frost's instructions. He is instructed to find a Zoomcar access card hidden by Frost in an air grate. Janis and the other agents pursue him, but can't get to him in time. Mark enters the Zoomcar and receives a call from Frost on the car phone. Frost tells him not to alert the agents, and where to go.
At the courthouse, Zoe has gotten Alda a hearing. Zoe asks the judge to have Alda checked for appendicitis. The judge disagrees, calling it a frivolous claim, threatening to impose sanctions on Zoe, and then denies her claim. Alda says they didn't have to win in court for her to talk. She says she doesn't know where Demetri is, but says in her flash-forward, that they found his body in a building seven. As Zoe presses her for an explanation, the window behind Alda explodes. Alda dives out of it, making her escape and leaving Zoe bewildered.
With 90 minutes left, Mark runs up the mountains in the Antelope Valley. Frost comes up to Mark, saying its time for them again to save the world and points the gun at him. Frost tells Mark most of his associates wanted Mark dead by now, but Frost held off because he wanted to see things through to March 15. Frost tells Mark finding the mole does not make him safe. Mark disarms Frost, and forces Frost to the ground, pointing a gun in his face.
Frost tells Mark that he gave Charlie all the answers to find Demetri and that the whole world is running out of time. Frost stops talking, and in the distance, the glint of a motorcycle catches his eye. Mark stares in shock as Alda kills Frost with a sniper shot straight to the head and speeds off. Mark holds a dying Frost, who says he did what he did for a reason, and dies without giving Mark any information. Mark finds Frost's bag, takes everything and leaves the dead Frost. With 43 minutes left, Mark checks Frost's previous addresses in the G.P.S. One of the streets in Frost's G.P.S. matches the name of the painter of Oedipus & Sphinx, Ingres, and Mark heads that way.
At the morgue, the coroner says there are no identifying marks on the dead homeless man. The coroner looks at the dead man's brain, and deems that by its size, the man may be a savant. Olivia insists she is not connected to the man, but the agent insists she is, she just doesn't know it. At the hospital neuroscience center, the agent and Olivia talk to a Doctor Ebbing, whose address book was stolen by the man, to try to see if he is a savant. The doctor does not know and cannot I.D. the specific patient. He tells them that savants can have photographic memory, being able to record almost anything that they see.
With 4 minutes left, Mark arrives in an industrial complex full of warehouses. As Janis and Stanford try to locate Mark, he finally gets cell service and calls them saying he is at an abandoned army depot. Stanford and Zoe tell him to look at building seven, where he finds Demetri strapped to the death trap. Mark puts his finger on the gun in an attempt to move it, even if he can't disarm it, so it doesn't hit Demetri. Mark then realizes what is happening is just what the lady in Hong Kong said — it is Mark's hand on Mark's gun, which would kill Demetri.
Mark tries to disarm the gun again and remembers the Dr. Seuss poem, 1 fish 2 fish red fish blue fish, which tells him the order in which to pull wires. Mark pulls the red wire, then the blue. He manages to move the gun. It points straight at Demetri's forehead with 3 seconds left. The clock expires and the gun fires. Mark looks up to see Demetri is still alive. The bullets from the gun hit Demetri's photo on the wall.
Mark looks at the Garden of Forking Paths map. Demetri tells him Frost said they can decide different futures, and that the garden shows different futures. However, when Demetri stands up, the sprinklers go off, completely erasing the Garden of Forking Paths from the wall.
Olivia is approached by a man (guest star James Callis), who knows exactly what Olivia is going to order. He says his name is Gabriel, and he has stood behind her many times on this day. He repeats himself consistently, but says he wants to talk to her about the Raven River experiments. He says these are experiments his friend wanted to talk to her about, but his friend (Frost?) is now dead. The agent tries to get him to come in, but the man runs off, saying the dominoes are falling.
At the army warehouse, Demetri is reunited with Zoe. Stanford congratulates Demetri on getting through the day. Janis sees the destroyed Garden of Forking Paths and Mark says it could have been their key to the entire investigation, as Frost listed hundreds of different futures, all the moments he saw. Mark then reveals that there were events on the garden that occurred after April 29. Mark remembers one event specifically, and says that many different futures seem to lead up to it. The date is December 12, 2016, and it is titled "the end." Mark doesn't know what that means.
Frost admits that there are multiple possible futures and that flash-forwards are not a guarantee. Now, the question is whether decisions people make, knowing their futures, will lead to those futures like a self-fulfilling prophecy, or simply create new ones. This opens up the possibility for alternate universes with these futures (similar to Lost). How does Demetri not dying change for the future? And who is Hellinger? Who are he and Alda working for? Was Frost ever even the bad guy, or was he trying to escape & help? And, of course, who the heck is Gabriel?