Warning: The following is speculation based on information from The Strain's book and TV incarnations. Spoilers are present, so if you're not current, feel free to come back once you've caught up.
This weekend marks the end of The Strain, as the final episode of the series is set to air on Sunday night. With everything coming down to one last call of action and drama, The Master's hours would be presumably numbered. After all, the death of the greatest vampiric evil in the world has been the goal for the show's resolution, ever since it started back in 2014. But just how can you kill a being that's already been attacked by silver, sunlight, and pretty much anything else that's been thrown at him? Well, there's a pretty good chance we know how, thanks to the events of Season 4.
Unpacking the potential demise of The Master, Season 4 of The Strain has turned back to the sacred text of the Occido Lumen, the mysterious book that details the history of vampire lore and how to defeat them. For a while, there was talk about "the face of God" being the force that destroys the head vampire in charge. Naturally, with Fet's quest in the west to procure a nuclear warhead, the big assumption has been that this biblical sounding revelation is hinting towards a force of great devastation. With the right yield on the device now smuggled into New York, this would be pretty damned easy.
But a couple of weeks ago the story of how The Master would die took a bit of a turn, as Professor Abraham Setrakian was convinced that this prophecy may have been wrong in its prediction. Before he died, Setrakian mentioned that an act of self sacrifice was going to be the key to destroying the entire vampire hierarchy, almost completely dispelling the notion of an atomic bomb. This sewed dissent among the ranks, and ultimately the worth of said nuclear warhead has been disputed. But if you turn back the knowledge of The Night Eternal, the final book of The Strain trilogy, both of these halves match up to show a picture of the end.
In the third and final part of the literary source, a nuclear bomb is still the ultimate force of destruction that takes out The Master. But this comes after a confrontation that sees him wounded badly which involves Quinlan, Zach, and Eph. After turning Quinlan to a full Strigoi, The Master goes to turn Zach into his new earthly host, but not before Eph flips the switch and nukes all involved out of existence. One last touching moment where Zach calls out for his dad, and Eph realizes how much he loves his son, is all that remains before the explosion takes them all out.
So right there, in the story of The Night Eternal, the "great personal sacrifice" already exists, and the nuclear warhead does end up coming in handy. But, just to be sure, let's take a look at the preview for the finale, and see what we can pick out for ourselves.
There's some key details that look like they support this hypothesis of The Strain's ending from the book series being used. We see Quinlan collapsing after some sort of an attack that weakens him, as well as The Master preparing for the ritual where he vomits worms on his next form, in order to transfer the special "Master Worm" to his chosen vessel. But most telling is the sad goodbye that looks to be happening between Eph and Dutch, which is followed immediately by Fet looking down at the camera, and later by Dutch crying, and the two remaining hunters trying to stop something from happening.
So how's The Strain going to end? Here's what it looks like will happen: the sub-level of New York will be the final playground of destruction. Quinlan, Eph, and the nuke will descend into the killing field, and ultimately the confrontation of fathers and sons will take place. Quinlan and The Master will fight, with Quinlan being overtaken by The Master, and Eph and Zach will more than likely fight before The Master tries to turn the young man. Eph will trigger the nuke, set to just the right yield that only takes out our key players underground, and his tremendous sacrifice will save humanity.
Of course, this could be proven wrong when The Strain airs its final episode, "The Last Stand", this Sunday at 10 PM EST on FX. But whether we're right or wrong, we're ready to see just how this ends.