An unidentified person scatters a deer carcass in a trail leading up to the prison. As walkers follow the bait, the person then breaks open the prison gate, placing the deer's heart in front of it.
The survivors are discussing plans to clear out the prison yard when Axel and Oscar approach, begging to join the group. T-Dog is in favor of letting them, but Rick insists they keep to their cell block.
In Woodbury, Michonne inspects the salvaged National Guard trucks, noticing bullet holes and blood traces. She questions the Governor about the circumstances of the soldiers' deaths. He dodges her suspicions and tries to convince her and Andrea to stay in Woodbury.
Back at the prison, Rick instructs Glenn to give Axel and Oscar a week's worth of supplies and send them away. Axel tries to ingratiate himself with Daryl by offering to tune his motorcycle, but Daryl ignores him.
Meanwhile, Beth and Lori help Hershel hobble out of his cell on crutches.
In their room, Michonne and Andrea discuss plans to head for the coast after leaving Woodbury. "I'd rather take my chances out there than stay here," Michonne declares. "Because your gut tells you there's something off about this place, about the Governor?" Andrea asks.
As Rick and the others clear the yard, Lori and Carl escort Hershel outside. The group rejoices at Hershel's recovery, but is soon interrupted by attacking walkers, which have infiltrated the courtyard.
Gunfire erupts as Rick races to join the fight. Hershel and Beth lock themselves inside a fenced-in entryway while Maggie, Lori and Carl flee into the cell block.
While resealing the courtyard gate, T-Dog gets bitten in the shoulder.
Back in Woodbury, Andrea shows Merle the location of Hershel's farm so he can look for Daryl. When she declines his offer to join, he remarks that they were both abandoned - and then rescued - by the same two groups of people.
Andrea asks Merle if the Governor is a good man. "I wasn't in the best of shape when he found me," Merle replies. "He should've just kept on going. Yeah. He's a good man."
In the prison yard, Glenn reports that someone cut the gate open. When Axel and Oscar approach, Rick accuses them. Just then, the prison's alarm sounds, attracting more walkers to the fence. Oscar explains the back-up generators must be powering it - proving that someone else is messing with things inside the prison - and follows Rick inside to disable them.
Wandering the prison hallways, Carol offers to "do whatever's necessary" to help T-Dog with his bite, but he insists on guiding her back to the cell block.
Lori, Carl and Maggie are also wandering the prison when Lori doubles over in pain: the baby is coming. Carl leads them into the boiler room.
Meanwhile, Merle asks the Governor for permission to go search for Daryl. The Governor says he can't risk losing Merle on a wild goose chase, but agrees to let him go if he can obtain more concrete information.
Back at the cell block, Rick, Daryl, Glenn, Axel and Oscar separate into teams to look for the others and shut down the back-up generators.
In the boiler room, Maggie helps Lori get ready to deliver the baby. But as Lori pushes through her contractions, she begins to hemorrhage.
T-Dog and Carol reach the laundry room doors, but are blocked by walkers. Out of ammo, T-Dog charges them and urges Carol to keep going. She reaches the doors, but looks back in horror as the walkers tear T-Dog apart.
Back in Woodbury, Andrea and the Governor share a parting drink in his apartment, where he reveals his real name - Phillip - and that his wife died in a car accident before the apocalypse. Before Andrea leaves, the Governor tells her she can return to Woodbury any time.
Rick, Oscar and Daryl reach the generator room, where they find Andrew - still alive and waiting to attack them. As Andrew and Rick struggle, Oscar picks up Rick's gun. Andrew urges him to shoot Rick, but Oscar shoots Andrew instead, then returns the gun. Rick powers down the generator.In the boiler room, Lori grows faint as the hemorrhaging continues. "I'm not losing my baby," she tells Maggie. "You've got to cut me open."
Back in Woodbury, Andrea tells Michonne she wants to stay longer. Michonne storms out.
Lori tearfully says good-bye to Carl. "Don't let the world spoil you," she says. "You're the best thing I ever did."
Maggie slices Lori's belly open and scoops the baby out. The baby survives, but Lori lays motionless, blood pouring from her open wound. "We can't just leave her here," Carl says. "She'll turn."
Maggie leaves with the baby as Carl hugs his mom. Moments later, outside the room, Maggie hears a gunshot.
Outside, Rick, Daryl and Glenn reunite with Hershel and Beth. Maggie and Carl emerge with the baby. Rick collapses in grief when he realizes Lori is not with them.