This is the fourth season finale! No spoilers, so please DO NOT spoil anything in the commentary section.
"A" is the last episode of TWD's season 4. It starts with a flashforward of Rick being devastated after a fight that has just happened. After this scene, the action begins with the group staying by the woods and trying to survive.
The group led by Joe makes a successfull ambush on Rick's group. With a huge quota of sadism, Joe tells Rick Daryl is going to be beaten to death, Carl is going to be raped, Michonne killed and finally Rick is gonna die. However, Rick saves Carl from being ripped and gets caught again. In that moment, Rick bites Joe to death and Michonne takes advantage of the levarage to kill two of the attackers group.
After overcoming the situation, a part of the group enter Terminus. Just a minutes after being inside, some people living there make Rick and his fellows leave the weapons and listen carefully.The facilities are shown and all seems just fine, but Rick discovers that people from Terminus has some elements from Glenn and Maggie The group manages to flee but they're soon caught again. The episode ends with Rick, Michonne, Daryl and Carl meeting again with Glenn, Maggie, Bob and the rest of the survivors inside a boxcar.
Interesting facts: an epic finale is delivered by Rick's words: "They're f***ing with the wrong people". "A" is the shortest episode title ever and it refers to the different signs leading Terminus. Did you notice this is the first time Michonne kills a living person with a gun?