Wondering who called Rick, and why? Rick's a little curious about that too, but he's more interested in talking the group at the other end of the line into taking in his own group. Unfortunately, with no caller ID or star 69, he's at their mercy, and they have a rude habit of hanging up on him. So he basically spends almost the entire episode hanging out in the boiler room, having increasingly mysterious conversations with different voices on the phone. The fourth person who calls him explains that the people he's been talking to include Amy, Jim, and Jacqui, and that fourth person is Lori. Yep, it's a magic phone to heaven. Rick gets to explain himself to the ghostly voice on the line and find a little closure. The connection breaks up before Lori can tell him what he needs to do, but I think he's figured it out.
The Governor has sent Merle and a search party out after Michonne since her departure from Woodbury. She quickly kills two of them, leaving only Merle and one other guy alive. After some cat-and-mouse-and zombie in the woods, Michonne is wounded and covered in walker guts, but still on the loose. Merle kills his remaining compatriot rather than continue to go after her, and goes off in search of a car to drive back to town.
Maggie and Glen hit an abandoned town on a run for supplies, primarily baby formula. Coincidentally, they're observed by Michonne, who stays out of sight. She also observes as they're met by Merle, who's pretty happy to see Glen and asks to be taken to see Daryl. When Glen says that's not going to happen, Merle gets violent, kidnapping both Glen and Maggie and forcing them to drive him back to Woodbury (where the Governor and Andrea are, by the way, screwing. Gross). Michonne was clearly in no condition to mix it up with Merle again for two people she didn't even know, but it's not as if she does nothing; she personally delivers the formula to the prison. Presumably she'll also deliver word of what became of Glen and Maggie, but that'll have to wait until next week.
Merle With Bayonet Attachment leads a party of three other guys through the woods. Apparently they're on a search for Michonne, but in a clearing they instead find a little message she left them, in the form of parts of a sliced-up walker neatly arranged on the ground. It takes them a moment to figure out that she's spelled out "GO BACK" using arms for the G, legs for the O and an actual back. Merle's delighted: "She sent us a biter-gram, y'all!" One of the guys is a little freaked out, so Merle tells him to get his shit together. Also, his name is practically unpronounceable -- something like "Gardjuilio" -- so Merle's just going to keep calling him Neil. Works for me. Hearing a sound in the trees, they all draw their weapons. Merle calls Michonne out, and a moment later she drops from the trees and kills two of the men with her katana before Merle can turn around, then uses one body for a shield and darts into the woods while he fires his automatic at her. He clips her in the leg and leaves Neil freaking out with their dead buddies. Merle reaches another clearing, where there's no sign of her. "We having fun yet?" he bellows into the woods.
And now we're back inside the prison, traveling through the corpse-littered hallways to where Rick is on the phone to what sounds like a young woman. She says they can't believe someone answers, and that they've been calling since the beginning. She's not saying where she and her friends are, just that they're "Away from them." Rick tells her he has a son and a newborn and a good group and asks if they could take them in. She says she needs to talk to her group, and Rick gets desperate, crying that they need help. "We're dying," he whispers. "We're dying here." She hangs up, promising to call back in two hours. Hey, speaking of calling people back, has Rick completely forgotten about Morgan? I guess waking up at sunrise every morning must get pretty tiring.
Back in the cell block, the rest of the group's eating gruel. "Everybody okay?" Rick asks, coming in all cleaned up and saying he just wanted to check on Carl before going back to get rid of the bodies in the boiler block his own self. He seems satisfied to hear that Axel's working on the generators and that Glenn and Maggie are making a run later to find ammo and baby formula, so he stomps back out. Well, thanks for checking on everyone.