This is the first half of a two-part season finale involving a prolific serial killer.

: The BAU investigates a series of disappearances in Detroit after an Iraq War veteran, William Hightower, crashes the Canadian border to force an investigation into his sister's disappearance.

: Marinette discovers that Adrien is being forced to leave Paris for several weeks on a worldwide tour with Lila.

: Despite severe injuries, Endeavor pushes his limits with a "Plus Ultra Prominence Burn," incinerating the Nomu in the sky.

: " In Theory ." Data attempts to program a romantic relationship for himself with a fellow crew member, while the ship experiences space-warping anomalies.

: The episode ends as the team realizes the "mastermind" they found, Mason Turner, is a bedridden quadriplegic, and the actual killer is his massive, younger brother.

: The episode ends with a cryptic dream sequence where Izuku meets the previous users of One For All, including the first user, who acknowledges him as the ninth.

: Under Risk's influence, Marinette nearly reveals her secret identity to Adrien to stop him from leaving. Other Notable S4E25 Episodes