PITTSBURGH -- The debut season of Fox's "The Passage" - based on the trilogy of books by author Justin Cronin - has been speeding toward the two-hour season finale, promising something grand and apocalyptic at the end.
Monday night it delivered on that promise, offering a major cliffhanger for a yet to be announced second season.
The two-hour finale picks up where it left off with the "viral" vampires out of their cages and attempting to break through the barrier wall at Project NOAH.
In an attack, Dr. Lila Kyle (Emmanuelle Chriqui) is bitten and infected, providing the first major twist of the night.
As the others escape, federal agent Brad Wolgast (Mark-Paul Gosselaar) returns to the compound to retrieve the virus antidote, held by Dr. Major Nichole Sykes (Caroline Chikezie) who is trapped in a lab.
Wolgast gets to Sykes to retrieve the medicine but they eventually find themselves locked in one of the "viral" cells.
Meanwhile, the others begin wrestling with the decision to pull the plug on the entire operation which would require the activation of a bomb below the "viral" holding area. This decision proves difficult because it would mean losing Wolgast and Sykes in the process.
Ten-year-old Amy Bellafonte (Saniyya Sidney) - the show's most important character - makes the decision herself, initiating the bomb and destroying a large part of Project NOAH.
Wolgast is able to escape with the antidote just in time, saving Kyle, however Sykes decides to stay and is lost.
As the first hour winds down, Wolgast, Kyle, Bellafonte, Clark Richards (Vincent Piazza) and Dr. Jonas Lear (Henry Ian Cusick) are on the run away from Project NOAH, but they fast realize the blast did not take down "the virals," indicated by the fact Bellafonte is still alive and well, given her physical connection to the others.
Leader of the "virals" Dr. Tim Fanning (Jamie McShane) is seeing his master plan play out, with the vampires loose and on a path of destruction with a goal of ending the world.
Meanwhile, Richards continues to be haunted and hunted by the "viral" he has grown particularly close to, Shauna Babcock (Brianne Howey).
Babcock spares Richards' life but in exchange selects him as the one human she can save, pulling him into her world in present day Las Vegas.
As the final hour begins, Lacey Antoine (Kecia Lewis) - Wolgast's trusted colleague from the past - re-enters the story and forces Lear to commit to finding a solution to the Project NOAH disaster he created instead of giving up.
After the destruction of Project NOAH and the release of the "virals," we learn Wolgast, Kyle and Bellafonte are now living in secrecy in the Oregon wilderness, far from the "viral" attacks happening across the country.
Their new temporary family could be the last hope for mankind, as they hold the only virus antidote on the planet.
Kyle then learns she may be immune to a "viral" attack after receiving the antidote and makes the difficult decision to leave Wolgast and Bellafonte for the opportunity to help find a widespread cure.
Elsewhere, the "viral" takeover is spreading from major city to major city, creating a national crisis and putting the rest of the world on notice.
While this is unfolding Lear is working on an antidote that can be mass-produced, but Fanning continues to haunt him in a mindscape. Fanning also visits Bellafonte and reminds her she would be willing to go to great lengths to protect those she loved, even if it meant harming others.
Bellafonte denies she would ever turn violent but Fanning is eventually proven right.
Lear is then put in front of world leaders and questioned about the virus spreading beyond United States borders. Unhappy with his reports, a nuclear attack against the U.S. is ordered. As a last-ditch effort to test his new antidote, Lear injects himself.
Meanwhile in Las Vegas Richards and Babock continue to occupy both worlds, with Richards supporting Babcock's "viral" existence.
The climactic moment of this debut season then comes when Bellafonte is forced to protect Wolgast after he is attacked by a neighbor turned "viral."
When other neighbors decide to stop Wolgast from turning by killing him, Bellafonte uses her vampire powers for the first time, saving Wolgast who then gives himself the antidote.
As promised throughout the season the end of the world eventually comes following a nuclear bomb explosion.
The scenes then move forward 97 years into the future with Bellafonte having survived the apocalypse.
The season ends as Bellafonte explains "humanity is almost gone, but there is a place where people have managed to stay alive, maybe I will find you there."