Martha sits next to the car. A figure walks toward her. She starts to ask for help until she realizes it's a walker. She brutally kills it with a rake.
Martha holds her husband's hand and assures him that someone will help. The next morning, he dies and reanimates, and a heartbroken Martha puts him down. In the night, she buries him and is driven insane.
The next day, a truck pulls over at mile marker 54. The driver, Stevie, places a supply box on the ground and writes an accompanying note. Martha introduces herself and corrects the grammar on Stevie's message. Stevie thanks Martha for helping. "I don't help," Martha says as she stabs Stevie's throat with a stick.
Another truck driver leaves a supply box on the road. Martha ambushes him with a zombified Stevie, killing him. The following days, she kills several more truckers by attacking them with other turned truckers.
One day, Martha ambushes a truck driver, Purvis, and demands to know the identity of Polar Bear, the person who organized the box distribution. When the man refuses to answer, she kills him and tries to contact Polar Bear on the truck's CB. Morgan answers back and tells her he accidentally hitched a ride in the trailer.
Sarah, Wendell and Jim watch the SWAT van drive back toward the truck. The SWAT van stops. Al guesses that Martha used up all the ammo. Wendell opens his door and sees his wheelchair crushed on the ground.
Wendell shoots Martha in the chest and Morgan puts down Quinn before June can get bitten, when suddenly, the truck explodes and attracts a herd from the woods. Martha smiles and drives off in the SWAT truck as the group flees.
Some hours later, Alicia and Charlie discover the charred remains of the semi on the road along with several walkers corpses. Alicia consults a map and decides they will head east. She and Charlie get in their car.
Morgan and the others walk along the road with the herd in pursuit. June insists on checking everyone's injuries from the shootout. Morgan spots a sign for a hospital. Jim questions Morgan's leadership and refuses to go to the hospital with the group. He changes his mind, however, when he sees the herd getting closer.
At the hospital, Morgan guards the entrance, which he's barricaded with furniture. June updates him on everyone's condition and assures Morgan that he made the right call in taking them to the hospital.
Al, Sarah and Wendell find a set of walkies in a hospital room. Al asks Wendell how he ended up in a wheelchair. He explains that he got hit by a car as a child after he tried to save another kid from being hit. Later, Marines rejected him because of his handicap.
Elsewhere, Alicia and Charlie run out of fuel. They abandon the car to look for more. After walking a few miles, Alicia finally admits to Charlie that she is not looking for Morgan and the others, but instead, she's taking Charlie to Galveston to see the beach for the first time.
In the hospital, Jim thanks Morgan for saving him before when the walkers suddenly break through the barricade. They flee and Morgan alerts the rest of the group that the herd is inside the hospital. He suggests they head upstairs.
Morgan leads the group onto a floor that is clear of walkers. They barricade the stairwell entrance. Morgan suggests they secure the other stairwells.
Al and Sarah look for a stairwell. Sarah tells Al that she quit the Marines after they mistreated Wendell. They find a stairway blocked off and filled with walkers. Morgan reports via walkie that a roof caved in on another stairwell. Luciana informs the group via walkie that the barricade won't hold much longer. Morgan suggests they take the elevator to the roof. Al and Sarah look for generators to start up the elevator.
Suddenly, some walkers attack Morgan and Jim. After some difficulty, Jim manages to kill a walker with a surgical tool. Sarah informs them via walkie that she and Al found the generators.
Al urges Sarah to rejoin Wendell while she turns on the generator.
June, Luciana and Wendell flee as the walkers break through the barricade.
The group meets at the elevators. The lights turn on and the elevator doors open. The group piles into the elevator just in time to escape the herd.
On the roof, Sarah tries to reach Al on her walkie but doesn't receive an answer. Jim finds that the fire escape is broken.
June checks Jim's injuries and realizes he has been bitten on the back. Jim reels from the news. June assures a saddened Morgan that he will find a way to get them out.
In the woods, Charlie insists to Alicia that they turn around to find Morgan and the others. Alicia explains that she wants to take Charlie to the beach because she needs something good to happen. They hear water nearby.
Alicia and Charlie arrive at a lake created by the flooding. Charlie finds John’s hat. They look across the water and smile.
- Hank (Alive and Zombified, Flashback)
- Stevie (Alive, Flashback)
- Purvis (Alive, Flashback)
- Quinn (Zombified)
- 3 unnamed truck drivers (Alive, Flashback)
- First (and last) appearance of Hank. (Flashback)
- First (and last) appearance of Stevie. (Flashback)
- Last appearance of Quinn. (Zombified)
- Last appearance of Purvis. (Alive, Flashback)
- The title of this episode, "MM 54", refers to Mile Marker 54, where Martha's husband, Hank, died and she began her rampage.
- The filthy woman's real name is revealed to be Martha.
- This episode is dedicated to Dwayne Haevischer.
- At this point everyone knows, especially Morgan, that walkers will eventually loose interest in an area such as a building if they can't see or hear anyone inside. So all they had to do was stay away from the hospital windows and keep quiet and the herd of walkers would start to lose interest and dissipate. Yet Morgan keeps standing right where the walkers can see him through the windows.