While trying to revive Hershel and hoping he doesn’t come to as a zombie, Rick, Darryl and T-Dog educate the survivors in the prison on what has happened to the world (ie the zombie apocalypse).
At first, the group of survivors are not very keen on sharing their food and living space with Rick’s group, but they come to an agreement and Rick, Darryl and T-Dog help them clear a cell for them to live in. During practice, a member of of the survivor group is scratched by a zombie and Tomas (the leader of the survivors) ruthlessly slaughters him.
Tomas subsequently throws a walker at Rick during practice, losing Rick’s trust, so in a very un-Rick like way, Rick kills Tomas and feeds another one of them to the zombies.
At the end, they have Axel and Oscar (mustache and “not begging for his life” guy) and they return to the cell just in time to realize that regardless of all the blood loss, Hershel is just fine. Way to step up for your lady, Glen, btw! Totally adorable.