Episode #1: "Pilot" - October 5, 2016
After lightning strikes the antenna for her father Frank's old ham radio, Raimy Sullivan begins to communicate with another man, who she realizes is Frank nearly 20 years earlier. They both quickly realize they are speaking to each other through time. Both are also police officers in their respective time periods; Frank, in 1996, is going undercover and Raimy investigates the cold case of a serial killer in the present, known as "The Nightingale" because he targets nurses. She also uncovers evidence that Frank, who died in a shooting during a botched sting operation, was set up by his superior Stan Moreno, the current deputy police chief. She helps prevent his death at the time, but sets off a butterfly effect that changes reality: Frank dies in a car accident, her mother is shown to be a Nightingale victim, and her boyfriend Daniel has never met her.
#2 "Signal and Noise" - October 12, 2016
Raimy informs Frank that her mother, Julie, will be a Nightingale victim. She urges him to warn her, but Frank is hesitant to jeopardize his shaky relationship with Julie and young Raimy. In their respective timelines, both he and Raimy investigate Thomas Goff, a Nightingale suspect who had a sexual-assault charge filed but dropped against him; Frank's visit in 1996 precipitates the escape of a girl named Maya that Goff kidnapped, exposing his crimes to his mother. In 2016, Raimy discovers that Frank's actions caused the Goffs to move away, and she can no longer find them. In a desperate attempt to convince Julie she is in danger, Frank leads her to the radio to speak with Raimy, who remains silent in fear of further changing their history.
#3 "The Near Far Problem" - October 19, 2016
In 2016, Raimy finds where Goff hid Maya under an outbuilding and encourages Frank to pursue that lead in 1996. Frank discovers that the underground space has been cleaned with bleach, and finds a footprint that leads him to the woods, where he finds Maya. Raimy becomes convinced that Goff is the Nightingale, but Frank has doubts. They each track down Goff in their own timelines, but in 1996, Goff steps into traffic to keep himself out of prison; he dies in the past and vanishes just as Raimy is about to murder him in a blind rage. The Nightingale case remains unchanged, confirming Goff's innocence. In 2016, Raimy refuses to attend her mother's funeral, straining her relationship with Satch.
#4 "Bleed Over" - October 26, 2016
In 1996, a young girl, Eva Salinas, is found wandering the streets, having escaped from the Nightingale after he abducted her mother. The traumatic experience keeps her quiet until Frank has young Raimy play with her at the park. She tells Raimy a secret: she saw the Nightingale's face. In 2016, Raimy learns that Eva has been abducted again, but eventually discovers that she has faked the whole thing for attention. Frank asks Raimy to describe the Nightingale sketch from her precinct and he, in turn, shows it to young Eva. She recalls the Nightingale stalking her mother and describes his vehicle, which Frank recognizes from the park. He tries to approach it, but the driver flees and later burns it.
#5 "Seven Three" - November 2, 2016
In 2016, Raimy discovers that her very first collar has been murdered and realizes that she remembers two versions of that day: one from the current timeline, where she and her father arrested him, and one from the timeline where Frank was killed, where she rode with Stan Moreno and found him murdered. Raimy's knowledge of both timelines further implicates Stan as a dirty cop, but she has no hard evidence to prove it. She and Frank use an unaltered file from 1996 to try and flip one of Stan's CIs in 2016. After Frank accuses her of cheating on him with Raimy's softball coach, Julie asks him for a divorce.
#6 "Deviation" - November 9, 2016
At Raimy's insistence, Frank uses the next Nightingale victim as bait. He saves her life, but the Nightingale escapes, knocking him unconscious and taking a family photo from his wallet. In 2016, Raimy speaks to a tipster in prison who specifically requested her. He introduces himself as Karl Pierce, a mentally unstable quantum physicist who claims to have discovered the same phenomenon as Raimy, which led him to kill his neighbor at the urging of his future self. He suggests that the only way to stop the Nightingale is to kill him in the past. Raimy dismisses him, but changes her mind after discovering that the woman Frank saved has become a Nightingale victim in 2016.
#7 "Break, Break, Break" - November 16, 2016
In 1996, Frank is approached by his former lover, Miracella Corrado, whom he met while undercover and is now seeking refuge from Stan, who had her brother Jay murdered to cover up his attempt on Frank's life. Discovering the affair, Julie retaliates by rekindling her relationship with Raimy's softball coach, Ted. In 2016, Satch wants to retire after his wife divorces him, but Raimy convinces him not to when they find a major clue to the Nightingale's identity. A new victim, Larissa Abbot, is found at an old Christian hideaway camp where she was a nurse in 1994 and Raimy determines that whoever killed her must have worked at the camp at the same time.
#8 "Interference" - November 30, 2016
After watching a press conference where Raimy appeals for information about the hideaway camp, a woman named Meghan Womack tries to contact her, but is prevented from doing so by the staff at the mental health clinic where she is held. Her stepfather, Deacon Joe Hurley, of whom she is terrified, is approached for information about the camp by the police. Raimy's date with her new boyfriend, Kyle Mosbey, is interrupted by a drunk Daniel, forcing Raimy to abandon Kyle so that she can take him home. He admits he cannot stop thinking about her and they share a kiss, but she leaves after finding the ring he plans to give to his girlfriend Claire. He later visits Raimy again and they have sex. In 1996, Frank searches Larissa's belongings with her family's permission, and learns she was friends with Meghan at the camp. He also finds out about Julie's affair with Ted, but eventually gives her his blessing to continue.
#9 "Gray Line" - December 7, 2016
In 1996, Frank sets up a sting to expose Stan's corruption, but Satch tips him off and Frank is warned not to mess with Stan again. Frank and Julie reconcile after she and Ted break up and he moves back into her house. Frank also tracks down a younger Meghan and learns of her suspicions that her stepfather Joe murdered her mother and brother. In 2016, Meghan escapes the clinic and calls Raimy, but is abducted. Raimy breaks into Deacon Joe's house and finds the skeletal remains of Meghan's mother; the Deacon attacks her and escapes, and a manhunt is launched. Raimy warns Frank that Joe is the Nightingale and must be killed to save Julie, to which Frank reluctantly agrees.
#10 "The Edison Effect" - January 4, 2017
Having finally identified Deacon Joe as the Nightingale, Raimy helps her father prepare to murder him. Frank goes along with her plan, but questions whether it will cause more harm than good to the timeline; Raimy insists that doing so is the only way to save Julie. Kyle winds up in the hospital after being injured in a pursuit, and he and Raimy share a tender moment. Meghan manages to call the police, who trace her phone to a remote cabin; despite Raimy's best efforts, Joe kills her and flees. After chasing him down, she murders him in cold blood and surrenders her firearm to another officer. Meanwhile, Frank succeeds in abducting Joe, but ends up in a car crash after receiving a call from Julie.
#11 "Negative Copy" - January 11, 2017
Joe escapes from Frank's car, foiling Raimy's plan. Her actions are subsequently investigated as misconduct, and her badge is confiscated. Fearing that Joe will target his family, Frank concocts a new plan to frame him for theft. Unfortunately, this results in an alternate timeline where Joe was never caught in the first place, erasing all of Raimy's progress. Realizing that he will almost certainly kill Meghan in 1996 to cover his tracks, they decide to find her. Julie covers for Frank when Satch comes by their house to investigate, but he eventually figures out that she's lying. Out of desperation, Frank plants a bag of cash in Joe's house and has him arrested, while Raimy breaks into his cabin in 2016, finding Meghan and her brother alive in the nearby woods.
#12 "Harmonic" - January 18, 2017
Raimy takes Meghan and Robbie to the hospital, where she learns that the latter has been living under an alias for 20 years after running away from home. Frank tries to get Joe to confess, but he fakes a beating and is allowed to leave. Raimy and Satch find the evidence needed to get Joe arrested, and Raimy gives him her shoelaces to commit suicide in return for the location of his wife's body, which Frank then uses to identify Joe as the Nightingale. Unbeknownst to him, Stan, who still harbors a grudge against him, steals an envelope addressed to Frank before leaving the crime scene. Raimy discovers that her mother is now alive in 2016, while Robbie, having been reunited with his sister by Frank, returns to his apartment in 1996 and inspects a collection of photos of Julie before going to sleep.
#13 "Signal Loss" - January 25, 2017
In the new timeline, Frank still dies in 2011, but Julie is now a doctor, Gordo is a lawyer, Satch's marriage is intact, there have been no Nightingale murders since Joe's arrest, and Raimy and Daniel are engaged. By chance Raimy encounters Robbie and becomes suspicious of him, and convinces Frank to visit Robbie and Meghan in 1996 and make further enquiries about Joe. This unbalances Robbie, who tells Meghan that he is the Nightingale and that Joe took the blame for him. Robbie murders Meghan and then attacks Julie, Raimy and Gordo, kills Gordo's father, and destroys the ham radio, cutting off contact with Raimy in 2016. Despite their mutual grudge, Stan races to help Frank rescue his family, but is shot by Miracella (to avenge her brother) before he can reach the scene. Frank is shot by Robbie, who tries to flee with a captive Julie, but Satch intercepts them and rescues Julie, though Robbie escapes. Raimy is relieved to find the present relatively unchanged in 2016, but Robbie remains at large.
On May 13, 2017, The CW released a 3-minute epilogue to the series to provide closure after its cancellation.