Walking Dead
Rick figured out who Karen's killer was in episode 3 of "The Walking Dead." Gene Page/AMC

Who is safe in the prison? By the end of the latest episode of “The Walking Dead” the answer might be no one.

Episode 3, “Isolation,” introduced some more threats looming over the prison while wrapping up the mystery of who killed Karen and David … and the answer might shock you.

Check out our short recap with the top five moments from the latest episode of “The Walking Dead”:

Getting A Little Rowdy

“Walking Dead” fans have watched cool and collective Tyreese refuse to fight and be a gentle giant. That all changed in episode 3. “Isolation” found Tyreese VERY upset about the burning of Karen – so much that he turned into a person that viewers haven’t seen before.

“You find out who did this and you bring them to me,” Tyreese bellows to Rick. “You bring them to me.”

Blinded by his rage over the death of his girlfriend, Tyreese doesn’t take kindly to Daryl and Rick trying to talk him down. Instead of walking away, Tyreese attacks Daryl and then Rick. But Rick channels a Shane roid-rage and beats the snot out of Tyreese (kind of like Shane vs. Carol’s husband Ed in season 1).

The Sick Are Growing

The outbreak didn’t end with Karen and David being burned alive. The prison now has a whole corridor filled with the sick – some coughing up blood, others shaking and a couple even turned to walkers. With the numbers growing, the council decides that they must quarantine the sick and keep the healthy young and elderly away from the others in a separate building.

Sasha, Glenn and Lizzie (the young girl now in Carol’s care) are the latest to come down with the symptoms that killed Patrick. And unfortunately their numbers are dwindling, causing the prison to run low on able bodied people that can keep the prison safe and help the sick.

With Dr. S also ill, Hershel steps up to the plate to help – despite his daughters begging him not to. Hershel informs the others that the illness is not what kills, but instead the symptoms. With that knowledge, they hatch a plan: Send Daryl and a team to a veterinary school 50 miles away to look for supplies while Hershel tries to buy the sick time with a special tea from berries in the woods.

Carol’s Suspicious Behavior

With rage still boiling inside Tyreese he initially refuses to go on the medicine run with Daryl, Michonne and Bob. Instead he decides to keep watch over Sasha and the other sick people so that the person who murdered Karen and David don’t strike again.

However after realizing that the medicine is Sasha’s only hope for survival he agrees to go on the run. But not before asking Carol for a favor – watch over Sasha.

Explaining that he’s asking her because he sees how much she cares for the others at the prison, his comment sends Carol spiraling out of control. After he leaves, Carol begins to sob, knocking over their water supply and then deciding to do something stupid … go out into the walker-ridden fields alone to fix the water hose.

A Supply Run Turned Ugly

Daryl, Michonne, Bob and Tyreese head out towards the veterinary school but get distracted by a woman’s voice on the radio. “Sanctuary,” says the recording. “Those that arrive, survive.”

Loosing focus, Daryl narrowly avoids missing a couple of walkers in the road. Getting control of the car, they discover that the road ahead of them has hundreds – maybe even thousands – of walkers heading towards them.

Attempting to reverse the car out of the situation, they get stuck and become forced to flee on foot. And while Bob, Michonne and Daryl jump into survival mode, Tyreese seems to be frozen in the backseat. Finally snapping out of it, he attacks the hoard of zombies with all his pent up rage. Tyreese appears to get overrun by the walkers, leading Daryl and the others to continue without him and run into the woods. However their surprised when Tyreese manages to catch back up (although appearing a little worse for wear).

The Killer Revealed

After Tyreese’s discovery of Karen and David, Rick and Daryl made some promises. Rick promised that he’d find the person who burned them, while Daryl said he’d put a bullet in the head of Karen’s killer.

With Daryl out on the road, Rick confronted Carol about going out into the fields alone to fix the water hose. “It was a stupid thing you did,” he says to her, causing her immediately to stiffen. “Going out there like that.”

But as some viewers suspected, Rick’s confrontation was somewhat of a trick. Suspicious that Carol might have played a role in Karen and David’s death, he flat out asks her … and gets a simple “yes” as a response.

Were you surprised that Carol burned Karen and David? Let us know your thoughts on episode 3 of “The Walking Dead.”