Tomorrow's episode will take us back to the origins of Dexter's use of M99.
The first Dexter: Original Sin episode of 2025 is almost here, and fans couldn’t be more excited. Episode 5, titled “F is for F*ck-Up,” teases the aftermath of Dexter Morgan’s failed attempt to kill “Mad Dog,” an episode villain portrayed by renowned actor Joe Pantoliano.
Showtime has released a thrilling 2-minute sneak peek of the upcoming episode, featuring Dexter (played by Patrick Gibson) stirring up chaos at a horse farm—but with a calculated purpose. Having learned from his previous mistake with Mad Dog, Dexter is bringing back his most infamous tool: M99.
M99, also known as Etorphine, is a highly potent synthetic opioid commonly used to tranquilize large animals like horses and elephants. It’s thousands of times stronger than morphine and has been a crucial part of Dexter’s meticulous methods throughout the series.
In the 'Dexter-verse', M99 is Dexter’s sedative of choice, allowing him to incapacitate his victims swiftly and effectively before beginning his ritual. Fans of Dexter: New Blood may recall a similar scene where Dexter used ketamine after nearly a decade away from his dark routine.
This sneak peek clip also features two iconic scores by the late Dexter composer Daniel Licht, including the chilling Trinity Killer theme, which is sure to stir nostalgia for longtime fans.
Watch the sneak peek video below to see Dexter back in action and get a taste of what’s coming next!