This Sunday, The Strain heads into its fourth and final season. Created by Guillermo del Toro and Chuck Hogan, it’s a horror drama with enviable pedigree and made waves at the time of its premiere in 2014 with its unsettling ad campaign (most of the promo images for the first season featured a worm making its way into an unfortunate victim’s eye, which was eventually taken out of circulation due to complaints) and its new take on vampires. Since then, the show — much like the vampires on it — has mutated and changed. This has been equal parts good and bad news; the show’s inconsistencies haven’t really been ironed out, but the heights it reaches make up for the valleys.

Spoilers for the first three seasons of The Strain follow.

Strigoi Fever

The vampires on The Strain are known as strigoi. They’re parasites rather than paramours as they so commonly are in pop culture. Like their popular counterparts, strigoi can’t venture into sunlight, and are particularly affected by silver, but it’s there that the similarities end. The strigoi are just as novel as they are disgusting. As suggested by the ads, they proliferate via a type of capillary worm, and infection results in truly horrific changes that are cataloged throughout the show. The tongue turns into a proboscis, and hair, nails, and genitals (among other things) all fall off. Strigoi are also relatively mindless creatures, controlled by appetite and by hivemind rather than any autonomous thought. Granted, there are a few exceptions to the rule.

It’s Good Being Bad

The big bad of The Strain is an ancient vampire known only as the Master. Over the course of the show, he’s survived in classic parasitic fashion, i.e. by taking on new hosts rather than remaining in a single body. In his quest to take over the world, he’s chosen lieutenants — strigoi he allows a measure of autonomy and who pass for human with the use of makeup and prosthetics. His most prominent henchman is Thomas Eichhorst (Richard Sammel), who is consistently one of the most compelling parts of the show. This largely has to do with Sammel’s performance, which outshines the sometimes-dull material he’s given. His back-story as a former Nazi is rote, as is his role as the perpetual metaphorical bridesmaid, but it works due to how unafraid Sammel seems to be of being despised. And what fun is a story without a good villain?

Mommy Dearest

The Master’s second lieutenant comes in the form of Kelly Goodweather (Natalie Brown), the ex-wife of protagonist Ephraim “Eph” Goodweather (Corey Stoll). The series opens as they’re going through their divorce, and Kelly turns before the first season is through. It’s a storyline that’s only become more and more compelling as Eph (who was unwilling to go through with the divorce) has to reckon with the loss of his wife as well as the questions from his son, Zach (Ben Hyland in the first season and Max Charles thereafter), as to what’s happened to her. Ultimately, Zach ends up in Kelly’s hands, and it’s been a delight watching Natalie Brown play the conflict between human and strigoi nature as Kelly struggles between the protective instinct she still harbors for her son and the need both to feed and to follow the Master’s plan, which doesn’t really account for Zach’s wellbeing.

Beyond Thunderdome

One of the most interesting things about The Strain has been how ineffective its hero is. Eph is well-intentioned, but he’s shown to fail time and time again, to the point that his storyline feels Mad Max-ish in how he seems to lose each and every person who matters to him. Each loss takes its toll, too, as the show has seen him descend into alcoholism and a certain amount of self-pity rather than necessarily bucking up and getting through it. Again, it’s a gambit that works in large part due to the actor in the role (in this case, Corey Stoll, who manages to project a certain amount of strength and charisma despite how badly Eph is falling apart). Eph is sympathetic because he does about as well — if not better — than any of us might were we in his shoes. Dealing with the end of the world isn’t exactly easy, especially when those you love are working against you.

Women at the End of the World

Of the female characters, Kelly probably fares best. The hacker Dutch Velders (Ruta Gedmintas) kicks ass, but suffers for having her storyline tied largely to her love interests rather than her own merits. Nora Martinez (Mia Maestro), Eph’s colleague at the CDC and some-time flame, doesn’t fare much better, as she serves as a source of conflict for Eph before ultimately being fridged to further his existential angst. The tough councilwoman introduced in the second season (played by Samantha Mathis) doesn’t even make it all the way through the third. This isn’t to knock any of their performances — the cast of The Strain is fantastic across the board — but it points to a larger problem within the show, i.e. its large cast, while allowing for strange archetypes that normally wouldn’t get any screen time, also means that other stories get cut a little short.