Carol (Melissa McBride) warns Maggie (Lauren Cohan) about Alpha (Samantha Morton) and the Whisperers in a letter Maggie unearths in the opening minutes of The Walking Dead Season 10 finale, "A Certain Doom." Season 10 episode 14, "Look at the Flowers," confirmed Maggie did not know about the Whisperers or the horrors committed by the skin-wearing freaks, including the murders of Enid (Katelyn Nacon), interim Hilltop leaders Jesus (Tom Payne) and Tara (Alanna Masterson), and Carol's son Henry (Matt Lintz). Maggie has been away someplace far with Georgie (Jayne Atkinson), who years earlier supplied Hilltop with a "key to the future."
"Maggie, you need to come back. Jesus is dead. So is Tara. Enid. My son. They were murdered by a group called the Whisperers. Have you heard of them? They wear the skins of the dead and move in herds. Live with the dead," Carol's letter reads. "...When you come across walkers you need to watch hands for knives. Do not underestimate them."
In the remainder of the letter, mostly illegible, Carol writes "Alpha slaughtered" and "mark her border," referring to Alpha's attack against the communities that left ten dead, including Hilltop residents Tammy Rose (Brett Butler), Adeline (Kelley Mack), and Rodney (Joe Ando Hirsh). The victims then had their heads displayed atop pikes at the border marking Whisperer territory, a dishonor Carol avenged when she piked Alpha's decapitated and zombified head after the Whisperer leader was murdered by Negan (Jeffrey Dean Morgan).
Carol's letter goes on to mention Alpha "threatening to overrun us" with her walker herd, which Carol would later attempt to destroy when trapped in the cave hiding the thousands of walkers making up Alpha's army.
The letter was penned before the events of the Season 10 premiere, "Lines We Cross," where Carol reunited with Daryl (Norman Reedus) after months away at sea. Oceanside retrieved letters from Maggie, but Carol reported "there wasn't anything there, hasn't been for a while."
"When we continue, as everybody saw from the sneak preview, Maggie's back and she now knows what's happened to everyone based on that letter she got when Carol left her a note when she was traveling up and down the coast before the first episode," showrunner Angela Kang said on Talking Dead. "So we will find out what that means for our people."
The Season 10 finale could borrow from the comics, where Maggie once arrived at Alexandria only to find it overrun by Beta's walker horde.
The Walking Dead next airs "A Certain Doom" as a special episode later this year. For all things TWD, follow the author @CameronBonomolo on Twitter.