For “The Strain’s” final season, the monsters are in charge and that’s a good thing. The power shift from heroes to villains breathes new life into a show that stumbled after a promising debut. After a few uneven seasons, the series has regained its footing with a strong opening to its penultimate battle.

Enjoying the benefits of eternal night, thanks to disgruntled teenager Zach (Max Charles), whose daddy issues launched a nuclear winter, the Master (Jonathan Hyde) and his army of strigoi are no longer confined to the evening hours. As a result, much of the population is enslaved in a collaborate or die system, optimistically called “The Partnership” and the ragtag team of vampire fighters, Eph (Corey Stoll), Fet (Kevin Durand), Setrakian (David Bradley), Dutch (Ruta Gedmintas), Mr. Quinlan (Rupert Penry-Jones) and Gus (Miguel Gomez) are struggling to survive the new world order.

The action begins 9 months after Zach’s fateful decision. With Eph in Philadelphia, Fet and Mr. Quinlan searching the barren lands of North Dakota for a nuclear weapon to use against the Master, Setrakian in New York City and Dutch imprisoned in a strigoi breeding program, the story takes interesting new turns. Gone are the repetitive kill the bad guys/try to develop a cure scenes that weighed down seasons two and three. Separated and defeated, the main characters have to fight individual battles that take them into new territory.

There are still plenty of gross kill the monster moments as bullets cut down the vampires and their worm infested insides spill out. And the Master, who took the body of his right hand man’s mortal enemy last season, is still a menacing Dracula meets “Alien” figure. But the focus on collaboration and resistance sets the stage for more characters and more stories, giving the show a refreshed energy and pace. This season, Fet has a new love interest, Gus recruits his cousin to cement his place at the top of the criminal underground and Eph meets fighters who inspire him to get back in the resistance game.

Some elements remain the same and they work. Setrakian is still the grumpiest old man in television and Eichorst (Richard Sammel) as the fiendish but loyal servant desperate to be chosen by the Master as his next incarnation, is forever scheming to realize his dream. Fet remains the comic relief, quick with the one liners and his partnership with the vampire hybrid Mr. Quinlan has a certain charm. Mr. Quinlan: “Once again Vasiliy Fet falls into a pile of manure and crawls out smelling of roses.” Fet: “Well, that’s my superpower.”

“The Strain’s” larger themes — what it means to be a parent, to take action when faced with evil, to believe in something larger than yourself — give the series layers but ultimately what it has always done best is have fun while shining a light on those monsters hiding under the bed.

The final season of “The Strain” premieres Sunday, July 16 on FX.

— Melissa Crawley is the author of “Mr. Sorkin Goes to Washington: Shaping the President on Television’s ‘The West Wing’” and the recently released “The American Television Critic.” She has a Ph.D. in media studies and is a member of the Television Critics Association. To comment on Stay Tuned, email her at staytuned@outlook.com or follow her on Twitter at @MelissaCrawley.