Rick Grimes (Andrew Lincoln), Lori Grimes (Sarah Wayne Callies) and Carl Grimes (Chandler Riggs) reunite in episode three of season one. The series opened with Rick waking up alone in a hospital bed and discovering that the world is overrun by zombies and that his family is missing.
Andrea's (Laurie Holden) sister Amy (Emma Bell) dies in episode four of season one after a zombie bites her as the survivors' camp is surprised by the unexpected walkers while Rick is away. Carol's husband is also killed by zombies in this episode. In the next episode, Amy reawakens as a zombie, and Andrea kills her.
Shane (Jon Bernthal), Rick, Otis (Pruitt Taylor Vince), Patricia (Jane McNeill), Maggie (Lauren Cohan) and Hershel (Scott Wilson) watch over Carl after he is shot by Otis during a hunting accident in episode two of season 2.
In episode four of season two, Daryl Dixon (Norman Reedus) searches for Sophia alone and comes across a Cherokee Rose. He later gives the flower to the little girl's mother, Carol, and tells her that the rose symbolizes mothers' tears on the Trail of Tears. In season three, Daryl places the same flower on Carol's grave after he believes her to be dead.
In the mid-season finale of 2011, the group of survivors finally find Sophia when Shane releases a group of walkers trapped in Hershel's barn, and the little girl emerges as a zombie. Rick reluctantly steps forward and shoots Sophia.
Dale (Jeffrey DeMunn), who fought for the group of survivors to maintain their humanity, met his end in episode 11 of season two after a walker -- the same one Carl failed to kill earlier -- wanders to the farm and rips the man's belly open. Daryl rushes to help, but ends up shooting Dale in the head to end his suffering.
In episode 12 of season two, Shane lures Rick into the forest with the intent to kill his best friend, but Rick ends up stabbing and killing Shane. As Rick turns around, he sees Carl aiming his gun at him. As the camera pans out, it is revealed that Carl is pointing it at Shane, who has risen as a zombie. Carl shoots and kills Shane.
In the season two finale, a herd of walkers, drawn by the sound of gunshots, swarms the farm. Rick and the gang try to destroy as many zombies as possible by burning down their once-safe farm. Jimmy and Patricia die during the escape, and Andrea is separated from the group.
In the season three premiere, Rick and the gang find the prison, which offers them a glimmer of hope for a safe place to live at last.
T-Dog (Robert "IronE" Singleton) is bitten in episode four of season three, but tells the group that it was just a scratch. Later, as walkers swarm T-Dog and Carol, he tells her he was actually bitten, then sacrifices himself so she can escape.
Lori says goodbye to Carl in episode four of season three, as Maggie prepares to give her a C-section after complications arise when Lori goes into labor. Lori doesn't survive, and Carl shoots her before she can turn.
Maggie and Glenn hold each other in episode four of season three after she emerges holding Lori's newborn daughter.
The Governor (David Morrissey) brushes daughter Penny's (Kylie Szymanski) hair as episode five of season three opens. As the camera pans around to show her face, it is revealed that Penny is a zombie.
Rick goes on a zombie killing spree inside the prison in episode five after learning of Lori's death. Rick finally finds himself in the boiler room where his wife died, but her body is missing. As he looks up, he discovers the bloated zombie who devoured her remains, and repeatedly stabs the walker in the belly before collapsing.
With Rick busy taking out his anger and sorrow on the zombies in the prison during episode five, Daryl steps up as a daddy figure to the new baby, feeding her and cooing, "Hey, little ass kicker" to the infant.
Daryl finds the previously assumed dead Carol alive in episode six, and carries the exhausted and dehydrated woman back to their group of friends.