|“|| Araya: "My friends, I don't think you're aware of your poor timing. Do you know what the "dark moon" is?"|
Lydia: "...The part of the lunar phase when the moon is least visible in the sky."
Araya: "But do you know its meaning?"
Lydia: "Some say it's a time of reflection... or grief..."
Araya: "Grief and loss, mija. I wonder why, when you and your friends have suffered so much loss, you would risk it again for someone like Derek Hale."
Stiles: "'Cause we don't like to lose."
Stiles and Lydia head into Mexico, looking for the Calavera hunters who they believe had captured Derek. When paying them off fails, Scott, Kira, and Malia take down their enforcers, only to be defeated by the hunters using Wolfsbane fog. The lead hunter, Araya Calavera, questions Lydia about her Banshee powers and Scott's True Alpha status before brutally interrogating Scott herself. Araya reveals someone attacked her hunters and captured Derek and through a vision via electro-shock, Scott learns that the person responsible is Kate Argent, Allison's formerly dead aunt. After determining that the McCall Pack may be able to help them better than their hunters, who had been killed by Kate during their search parties, Araya hires, Braeden, a mercenary, to lead the pack to La Iglesia, where Kate is believed to be hiding.
On the way to the church, Scott tells Malia and Kira about Kate's role in the Hale fire and deduces that Peter's attack must have allowed her to survive. After suffering a mysterious breakdown, Scott is forced to continue on with Braeden to the church, where they expect to find Derek, while the others stay behind to fix the Jeep. Malia finds a bone claw lodged in the machinery of the Jeep. Both groups suddenly come under attack by mysterious creatures wearing bone armor; Malia and Kira chase off one, while Scott uses his Alpha roar to scare off the other. Scott and Braeden find a teenage version of Derek.
- Tyler Posey as Scott McCall
- Dylan O'Brien as Stiles Stilinski
- Tyler Hoechlin as Derek Hale
- Holland Roden as Lydia Martin
- Shelley Hennig as Malia Tate
- Arden Cho as Kira Yukimura
- Jill Wagner as Kate Argent
- Ivonne Coll as Araya Calavera
- Meagan Tandy as Braeden
- Ian Nelson as Young Derek Hale
- Ian Bohen as Peter Hale
- Ivo Nandi as Severo Calavera
- Panuvat Anthony Nanakornpanom as Latin Hunter / Stunt Double
- Laura-Elise Barrett as Spectator (uncredited)
- Andrew Hernandez as Clubber (uncredited)
- John Klarner as Cory (uncredited)
- Monica Ramon as Nurse (uncredited)
- The title refers to Araya Calavera's mention of "the dark moon," otherwise known as the new moon when the moon is least visible in the night sky. According to Araya and Lydia, dark moons are meant to be times of reflection of grief and loss, a fitting symbol, since they are still dealing with the death of their dear friend Allison.
- It is revealed that, like the Argent Family symbol is the fleur-de-lis, the Calavera Family symbol is a stylized skull, which they carve into their bullet casings. This is especially appropriate due to the fact that "calavera" means "skull" in Spanish.
- Calavera Bodyguard - stabbed to death; killed by Araya Calavera
- Calavera Compound
- Araya's Office
- Club Bathroom
- Torture Room
- Beacon Hills Animal Clinic
- Exam Room
- Consuela's Café
- La Iglesia
- The Temple of Tezcatlipoca
- "Dechorro" by Deorro
- Stiles and Lydia enter the Calavera's club, looking nervously around at all of the dancers
- "3 Hours (Klion Tek Rework)" by Emika
- Araya talks with Lydia and Stiles as her guards come in and threateningly cock their guns
- "Cayendo" by Deorro
- Malia and Kira dance seductively with each other in order to blend in as normal humans rather than supernatural creatures invading the Calaveras' home
- "Elevated" by Deorro
- Severo talks to the DJ, who sprays wolfsbane vapor into the crowd
- "Jungle" by Jamie N Commons & X Ambassadors
- Braeden arrives outside the Calavera compound to lead the pack to La Iglesia
- "(Aftermath)" by Vancouver Sleep Clinic
- Kira hugs Scott goodbye before he leaves her, Malia, Lydia, and Stiles while he and Braeden go to La Iglesia