"Isolation" is the third episode of the fourth season of the post-apocalyptic horror television series The Walking Dead, which aired on AMC on October 27, 2013.

In the inner courtyard, Tyreese explains to Rick Grimes, Carol Peletier, and Daryl Dixon how he found the burned corpses of his girlfriend Karen and friend David.

After bandaging Rick's hand, Hershel Greene and the rest of the prison's council decide to quarantine those who are sick in Cell Block A and separate the elderly and the children.

Tyreese's sister Sasha, Lizzie the prison's doctor, Dr. Caleb Subramanian, and Glenn Rhee are among those who contract the virus and are forced to enter quarantine.

Hershel suggests that they could search a veterinary college for medical supplies, and Daryl, Michonne, and Bob Stookey volunteer to retrieve the medicine.

Tyreese, after guarding the infected survivors from Karen's killer, bids farewell to a sick Sasha and leaves with Daryl's group to get the medicine.

While driving to the college, Daryl talks to Michonne about hunting for The Governor when they suddenly hear a voice over the car radio repeating the words "Sanctuary... those who arrive...survive..." A distracted Daryl drives into a horde of walkers, forcing the group to leave their vehicle, except for a morose Tyreese.

Cornet explains that the "landscape" has shifted well, adding that many interesting plot lines were extended and raised for this episode, most importantly of the voice heard through the car radio.

Cornet criticizes the scene in which Darryl, Bob, Michonne, and Tyreese all survive their car's being attacked by a large horde.

He adds that the chance to see some of the show's main characters step up and try to save others in their hour of need was great to watch, particularly Hershel.