In a flashback, Gareth and the residents of Terminus huddle in a Terminus train car while marauders torture and rape members of their group outside. Alex laments posting "Sanctuary" signs, saying they left themselves vulnerable and brought the marauders right to them. "We were trying to do something good," Gareth reflects. "We were human beings."
"What are we now, Gareth?" Alex counters. Gareth has no reply.
In the present, Daryl informs Maggie that Beth was taken by a black car with a white cross on the back and that she is alive. Meanwhile, Rick and the rest of their group are imprisoned in the train car. They quietly build weapons using scraps stripped from their clothes and the car's interior. Their captors release tear gas into the car, catching them off guard.
Rick, Daryl, Glenn and Bob are brought to a human slaughterhouse, where Terminus residents begin bludgeoning and slitting other captives' throats in a disturbingly neat and precise manner, allowing the blood from their slit throats to ooze into a trough, presumably draining them of their blood before preparing them to be eaten. The first to be slaughtered is Sam – the young man Rick and Carol met on a supply run before Carol's exile.
Before Glenn can be killed, Gareth interrupts to interrogate Rick about the bag he stashed in the woods. At first Rick refuses to comply, but after Gareth threatens to stab Bob in the eye, Rick admits it's filled with weapons, including rifles, handguns, a compound bow and a machete. Of the latter, he tells Gareth, "That's what I'm gonna use to kill you."
The butchers behind Glenn prepare to kill him again but, before Glenn is hit with the baseball bat, gunshots are heard outside, followed by a massive explosion.
They arrive at a cabin where Martin, a Terminus resident, is setting up fireworks to deter walkers away from Terminus. Carol and Tyreese hear him mention members of the group on his walkie-talkie and hold him at gunpoint.
Carol takes Martin's explosives and sets off toward Terminus, slathering herself in guts from a walker to disguise herself. Tyreese, meanwhile, keeps watch on Martin in the cabin. Martin tries to convince Tyreese to take his car and leave with Judith.
At the perimeter fence, Carol sees Gareth's men drag Rick, Daryl, Glenn and Bob to the slaughterhouse. She fires at a propane tank within Terminus, then launches one of Martin's fireworks toward the breach, setting off a massive explosion. Walkers begin to swarm into the building and begin killing its residents.
In the slaughterhouse, Rick quietly cuts his handcuffs (fashioned out of rope) with a wooden stick that he hid in his sock. He frees himself and fights his way out with Daryl, Glenn and Bob.
Mary sees walkers flooding through a hole in the fence and runs inside to the memorial room. Carol, disguised as a walker, infiltrates Terminus with the herd.
Maggie, Carl, Michonne, Sasha and Abraham's crew anxiously wait in the train car as they hear the commotion outside. Chaos reigns as walkers feast on Terminus residents. Carol takes advantage of the confusion and shoots down Terminus snipers.
As Rick, Daryl, Glenn and Bob leave the slaughterhouse, they see human body parts suspended from meat hooks. Rick tells his group that if they come upon any other Terminus residents, they should kill them without hesitation. They hear someone screaming and banging from a storage unit.
En route to rescuing the other survivors, Glenn insists on opening another train car to free the captives inside. But when they do, a deranged man runs out screaming wildly before a walker attacks him.
Carol discovers a room filled with items pilfered from Terminus victims. She retrieves Rick's watch – which he had given Sam -- and Daryl's crossbow.
Rick's group ambushes a team of Terminus residents and takes their weapons.
Carol discovers the Terminus shrine. Mary confronts her and they struggle. As Carol gains the upper hand, Mary explains that Terminus used to be a real sanctuary until a group of marauders raped and killed her people. The lesson, Mary explains, is "You're the butcher or you're the cattle." Carol, unconvinced, shoots her in the leg and leaves her to be devoured by walkers.
Back at the cabin, Tyreese becomes distracted by approaching walkers. Martin gets a hold of Judith and threatens to kill her unless Tyreese steps outside. Tyreese complies, and Martin listens to his shouts as the walkers attack. Martin then goes to check if Tyreese is still alive; Tyreese bursts through the door and pummels Martin. Outside, the ground is littered with walkers that Tyreese has killed with his bare hands.
Back in the train car, Eugene reveals that before the fall, he helped engineer harmful diseases to fight other harmful diseases. He says his team devised a system that could kill all humans on the planet — and that same system might be able to kill off the walkers.
Rick's crew rescues the rest of the group from the train car. Newly reunited, they fight their way out of Terminus.
Rick leads the group to the weapons cache in the woods. He insists they go back to kill the remaining Terminus residents, but the others disagree. "The fences are down," Maggie reasons. "They'll run or die." Carol appears. Daryl runs up to Carol and hugs her tightly, both of them share tears of joy seeing each other being alive and well. "Did you do that?" Rick asks, embracing her as well and thanking her for saving them.
Carol leads everyone to the cabin, where Tyreese awaits with Judith. Rick and Carl sprint over and joyfully reunite with the baby, while Sasha embraces her brother.
As the group rests, Tyreese tells Carol that he killed Martin. Rick decides that they will get as far away from Terminus as possible. Abraham intends to tell Rick about their mission but not yet. The group follows the railroad tracks until they happen upon a Terminus sign. Rick crosses out most of the text and modifies it to read, "No sanctuary."
In a flashback, one of the marauders – the same deranged man released during the Terminus firefight – enters the train car where Gareth and the others are imprisoned. He throws Mary into the car and selects a young woman, who is dragged off to be raped again. Gareth comforts Mary but as he tells her its alright the man backhands him across the face with a flashlight and informs Gareth, "No, it's not." He leaves and Gareth vows to Mary that they will take back Terminus. "You're either the butcher or the cattle," he declares.
Months after Rick's escape from Terminus, a masked stranger marches down the railroad tracks. He stops to see the Terminus sign Rick modified, and hangs his head. The sign is a little more overgrown than when we saw Rick change it, implying that a few months have passed. The stranger removes his mask. It's Morgan. He starts to follow a series of markings on trees - a circle with an X inside - to an unknown destination. It is unknown who it was that left the signs.
- Justice Leak as "Knife Smock Man"
- Adam Boyer as "Bat Smock Man"
- Owen Harn as "Crazed Filthy Man"
- Anissa Matlock as "Twenty-Something Woman"
- Nelson Bonilla as "Knife Cut Face Terminus Guard"
- Lennie James as Morgan Jones
- Charlotte & Clara Ward as Judith Grimes
- Summer Williams Houck as Terminus Resident
- Aaron Kirschnick as Terminus Guard
- Preston Baker as Terminus Guard
- Duke Jackson as Terminus Resident
- Aaron Tarver as Terminus Resident
- Chris Critter Antonucci as Terminus Resident
- James Rodney Sims as Terminus Resident
- Joe Foley as Terminus Resident
- Chuck Steak as Terminus Resident
- Jennifer Badger as Terminus Resident
- Patrick Williams as Terminus Resident
- Greg Rementer as Terminus Resident
- Zac Nichols as Terminus Resident
- Michael Morrison as Terminus Captive
- Charles William Cook as Terminus Resident
- Unknown as Cynthia (Voice)
- Unknown as Chuck (Voice)
- Chris Harrelson as Walker
- Stephen Vinning as Walker
- Paige Hamby as Walker
- Tim Proctor and Celeste Lezcano as Walkers
- Butcher 1 (Alive)
- Butcher 2
- Crazed Man
- Poncho Girl (Off-screen)
- Numerous unnamed Terminus residents
- At least 3 Terminus captives
- First appearance of Martin.
- Last appearance of Sam.
- Last appearance of Mary.
- Last appearance of Alex. (Flashback/Corpse)
- This episode marks the return of Morgan Jones since his last appearance in "Clear". Producer Greg Nicotero stated that Morgan found the sign at least "a few weeks" after the group's escape from Terminus, and in the episode recap on the AMC website, the scene is described as happening "[m]onths after Rick's escape from Terminus."
- This episode featured a new opening sequence since the start of Season 3.
- This episode features the most deaths for a season premiere, with a total of at least 24 casualties.
- This is currently the most-watched episode of the entire series to date. Receiving a total of 17.28 million viewers, becoming the most-watched drama series telecast in basic cable television history.
- Despite being series regulars since Season 4, Emily Kinney (Beth) and Chad Coleman (Tyreese) are listed in the opening sequence for the first time. Despite being regulars as well, Sonequa Martin-Green (Sasha) and Lawrence Gilliard Jr. (Bob) are still listed under "also starring".
- This is the first episode featuring Michael Cudlitz (Abraham), Josh McDermitt (Eugene), Christian Serratos (Rosita), Alanna Masterson (Tara), and Andrew J. West (Gareth) as series regulars. Cudlitz is added to the opening sequence, while McDermitt, Serratos, Masterson and West are listed as "also starring".
- Emily Kinney (Beth) is the only member of the main cast to not appear in this episode.
- The title of this episode comes from the fact that Terminus isn't a sanctuary as it claims, and also from Rick's repainting of the Terminus sign so it reads "NO SANCTUARY".
- The first 4 minutes of this episode was released by AMC via their YouTube channel, a day before the initial broadcast, as a sneak peek to the episode.
- Carol mentions that the fire from Terminus has not gone out due to the color of the smoke, a nod to what Mika said to her in "The Grove".
- A reference to the "Sloth" from The Goonies was added in the episode.
- During the filming of the scene where the Terminus residents are slicing throats, Andrew Lincoln, Steven Yeun, Norman Reedus, and Lawrence Gillard Jr were not told about the prosthetic necks, and the oozing fake blood came out of it. It was for them to act as if they were surprised and as if they'd never seen anything like it.
- In the scene where Martin puts his hands around Judith and threatens to break the baby’s neck, those were actually the hands of the baby actress’ father.
- The walker that Shane sees in 18 Miles Out appears in the new introduction sequence.
- When Carol was about to shoot the gas tank at Terminus, we could see two Terminus residents run past the tank. But when the camera zoomed in and Carol fired the first shot, those two Terminus residents could be seen running past the tank again.
- The Terminus residents that pass by Rick and Daryl are shooting to where the hip of a human would be, rather than the head.
- When Rick shoots several Terminus residents with the assault rifle, the ejection port doesn't open during any of the shots.
- The train car where the group is locked is in a different position than it was in "A".
- In one of the final shots when the group is walking back along the tracks, Carl is seen holding Judith. However, he moves his hand from her hip several times leaving him holding her by just her head - it is quite obvious a doll is used instead of an actress for Judith in this scene.
- When Carol and Mary are fighting in the memorial room, when they are knocked over candles fall on the floor and are kicked about while still lit, it is clear these are fake candles.
- At the start of the episode when Tyreese and Carol are walking down the railroad tracks towards Terminus, they encounter a herd of walkers coming out of the woods. One of the first walkers to cross the tracks is a male walker wearing a burgundy sweatshirt with a rip in the middle. When gunfire erupts at Terminus, the walkers turn their attention towards it. In the next shot when they start to head towards the sound, we see the same male walker now in the middle of the herd yet to cross the tracks, next shot after that, we again see him at the front of the pack.
- When Rick thanks Tyreese, the cabin door is open after Tyreese had closed it as the group walked up. In next shot it is closed again.
- Rick describes his revolver as a ".44 Magnum" when talking about the buried bag of guns. However, the Colt Python he uses is chambered in .357 Magnum.