A chrysalis is seen in front of the lights of the park ranger station. Mona drives up and enters the building. She notices that the rear door is broken. Derek appears suddenly and puts a knife to her neck. Christina rifles through the cabinets and takes some Meals Ready to Eat (MREs). Derek asks which key goes to the boat. Mona says it's the red one. Derek forces her into an enclosed space. Mona says they can take the boat and go. She won't tell anyone that they were there. Christina replies by picking up a fire extinguisher and smashing it into Mona's head.
Kira is asleep in a hospital bed. Tom tells Mariel that he is going to find the people who harmed Kira. He says that Kira has had a bad heart valve since birth. That's why the lights didn't transform Kira into a hybrid. The lights only take people if they're "perfect." Mariel says that Christina is a murderer who should be in jail. Tom shouldn't have sent her to the island. He explains that putting Christina in jail would expose all of the transformed people in the town. He says that Derek and Christina are going back to the island. "This time they're going to stay there." Tom leaves while Mariel examines the puncture wound near Kira's collarbone.
Russell shows Mariel's MRI to Healey. The foreign body inside Mariel is like a third ovary, with tubes running directly to her uterus. Though she isn't pregnant, the ovary is a relatively new development. Healey has never heard of any hybrids giving birth. Russell wonders if they shouldn't be worried about the offspring, instead of the hybrids. Healey warns him not to overlook the hybrids. Szura is "as dangerous as any creature that's walked the planet." The hybrids are "wired to survive at any cost. And that cost will be us if we don't do something to stop it." Healey still hasn't found Szura. He wants Russell to kill Szura if Healey dies before finishing the job. While taking his insulin shot, Healey reveals that his real name is Alonzo. Mona calls Russell. She is sitting upright but her head is bleeding badly.
Russell hurries to help Mona. While driving to the station, he calls Larkin and says that he won't be able to attend the meeting with Mariel and the kids.
Larkin and Dave are taking Jesse and Rose to see Kira at the hospital. In front of Jesse and Rose, Dave says to Larkin, "So they're finally gonna do it, huh. Mariel's gonna tell them that her and Tom are aliens?" Jesse looks shocked and Larkin glares at him.
Russell helps out Mona. She says she'll be fine. She tells him that Christina attacked her and that she is at least five months pregnant. Russell says that's not possible. Christina wasn't even showing a few weeks ago.
Russell is angry at Tom for letting Christina go. Tom understands that the park is Russell's jurisdiction and he offers to help while Russell takes the lead role in the pursuit of Derek and Christina. Tom convinces him that it would be best to minimize publicity about the hybrids. If Russell blows the whistle, guys in white lab coats are going to take Mariel away. "Try having your kids forgive you for that."
Derek and Christina are riding along the water in the skiff that they stole from the park service station. Derek says that he couldn't be the father of Christina's baby since they've only been together for a few weeks and she is already so big. They are heading to an old hunting camp that his grandfather used to take him to. The boat runs out of gas and Christina begins experiencing the sharp abdominal pains again. The baby can clearly be seen moving inside her.
At the Homestead Memorial Regional Hospital, Mariel is meeting with Jesse, Rose, Larkin and Dave. Jesse thinks Mariel's getting divorced again. Mariel says the meeting is about Kira, her, Tom and the whole town. Larkin says that the lights in the water have made many people in the town "different." As Mariel tries to explain what's going on, Jesse asks if she and Tom are aliens. Mariel glares at Larkin and Dave. Dave tries to explain that he was just saying that they had changed, like going from a caterpillar to a butterfly. Jesse asks whether Kira's different too. Mariel gets upset and says Kira hasn't changed. Mariel says she's not an alien. Jesse asks "Then what are you? Because we've known you've been different for a long time. We just want to know what you are." Rose says, "Not a butterfly."
Russell and Tom ride up the river on an airboat. They spot the stolen skiff on shore. Russell heads into the foliage. Tom asks, "Hey Russ, uh, you relying on some old Indian-tracker, broken-twig thing here, or do you actually know where you're going?" Russell thinks Derek and Christina are trying to cross the state on water to avoid roadblocks. He suggests they stay near the shore. Russell says they could also be heading up north to Big Cypress Trail in the Big Cypress National Preserve. Tom says they don't need backup.
Derek and Christina are walking along the shore. Derek asks what she is going to name the baby. Christina only replies that she has felt like a prisoner her entire life, ever since she got married after getting pregnant at the age of 16. She gave her second child away after her husband disappeared in the hurricane. She doesn't want to be a prisoner anymore. Derek thinks she is talking about Szura's camp, but she is talking about children. Derek hears a rustling in the bamboo and goes to investigate.
Back at the hospital, Dave tries to convince Larkin that they can investigate the lights as concerned citizens, even though Larkin promised Russell that she would stay away from the story. Dave wants to know why the military is sitting back and watching the hybrids. He suggests that Larkin contact her friend Vince at the air base.
Russell finds a food packet, an MRE, in the vegetation, which came from the park ranger station. Tom pauses. He stands and concentrates. Suddenly he whirls to his right and grabs the arm of a man who had been hiding there. The man yells in Spanish. Russell calms him down and learns that he is a migrant worker from Honduras. He leads them to the small camp where the other migrant workers live. The hurricane destroyed their housing and the other workers won't let them live in the new camp. Russell and Tom walk by some fish and squid that are hanging out to dry. As they reach the water, the "other" workers emerge from beneath the water's surface. They have been spearfishing by walking along the bottom of the river.
Mariel, Jesse and Rose are waiting when Kira wakes up in the hospital. She asks if she's been changed. Mariel says no and that it's a good thing. Jesse walks out of the room. Rose explains that he's upset with Kira for not telling him about Mariel. Kira wonders why she wasn't changed. Mariel says that her father will explain when he gets back. Vince meets with Larkin and Dave at the hospital. The wing commander told Vince that Larkin was researching a story about corruption in the military. Dave says that the wing commander is lying. When Larkin snooped around the base before, she saw 100 titanium boxes in the hangar on the base. She saw a similar box at the helicopter crash site in the Everglades, in the wreckage of Lt. Paxton's helicopter. The Air Force took Lt. Paxton from the hospital. Larkin says that the helicopter crew may have encountered something extraterrestrial in origin.
Russell knows that the migrant workers that walked out of the river are hybrids. Russell and Tom learn that Derek and Christina were there. The human worker had been afraid to tell Russell because he thought he and Tom were like the others, the hybrids. The hybrid workers killed the worker's brother for stealing a piece of fish.
Russell and Tom convince the hybrid workers to share their food with the other migrant workers. Tom calls social services but doesn't call the coroner even though the body of the worker's brother is still lying on the ground. They find out that Derek and Christina are heading south along the river. Russell says that their tour has been "educational." Tom says that the migrant workers' camp isn't his "vision of the future" for the hybrids. Russell asks, "Then what are you doing to stop it?"
Andy Dennison, the social services worker, arrives at the migrant worker camp. There are eight workers, but there were nine, as Russell points out. Dennison asks what happened to the migrant workers. Russell nods his head at the hybrids and says, "Ask them."
Derek and Christina reach a run-down house. Derek lights a lantern inside the shack. Christina starts drinking and begins looking for a closet. She examines a rifle-cleaning rod. She says it's not as sharp as a hanger. Derek finally realizes what Christina has been making very obvious. She doesn't intend to keep the baby. Derek protests but doesn't stop her. Before she can begin, she bowls over in pain. She says that it feels like her insides are being torn apart....
It's nighttime and Russell and Tom continue their search. Russell wants to leave to talk with his children. Tom scoffs at his altruism and shock over the murder of the migrant worker's brother. "That's the thing I never understand about people. They're always so astonished when one person kills another, but it's in our nature. You think we're descended from the three guys sitting in the cave, sharing their buffalo? We're descended from the fourth guy that says 'Hey, why don't I pick up this club and smack these other three losers and then there'll be more meat for me.' That's our ancestor. That's survival. Survival's what it's all about." Tom sees the cabin and the lights are on.
Larkin and Dave arrive back home with Jesse and Rose. As she notes that school starts again tomorrow, a parked car flashes its headlights. It's Vince. He tells Larkin that he knows the wing commander is lying to him. Paxton was processed at the base the same night he was removed from the hospital. He was taken to Hangar 42, the building where Larkin had seen the titanium boxes. Vince gives her the access code for the base's backup server computers. All the base's operations keep copies of their files on the servers.
Russell and Tom approach the cabin with guns drawn. They find Christina inside alone--and no longer pregnant.
Russell calls a ranger to pick up Christina. She claims that she doesn't know where Derek is. The park service pickup truck arrives and Russell walks up to meet it. Tom asks Christina what she did to Derek. Russell opens the door of the truck. The ranger falls out with a massive wound in his back. Derek sneaks up from behind and points a gun at Russell's head. Tom grabs Christina's hair and points his pistol at Derek. After a brief standoff, Tom lets go of Christina and lowers his weapon. Christina takes Tom's pistol and gets in the driver's seat of the truck. Derek says that he has to leave since he now has a family to think about. As he opens the door to get into the truck, Christina shoots him with Tom's gun and drives off.
Dave is accessing the base servers on his laptop computer. He says everything leads back to Underlay. He finds photos of the debris from Tom's plane crash in 1996, stored in the same Hangar 42. Larkin and Russell are looking on at the screen. A former intelligence officer was one of the investigators-Eli Szura. Russell seems to recognize Szura's face.
Szura appears for the first time. Tom and Derek are with him. Tom explains that Derek killed a park ranger, something that complicates their attempts to lay low. Szura asks where Christina is. Tom says they'll find her, with Derek's help. Szura walks to the truck with Derek. Tom calls out to him and says "Don't lose anymore." Derek sits in the back holding his quickly-healing gunshot wound. Seated next to him are the hybrid migrant workers.
Russell drives up to Healey's trailer in the pouring rain. He yells that they found Szura. He walks in to find Healey on the floor, apparently dead from a head wound. Russell stands in the doorway. In the foreground, a moth emerges from its chrysalis.