'The Strain' Season 2 Spoilers: Season Finale Synopsis Released; What Will Happen In Episode 13?

Throughout Season 2 of "The Strain," Setrakian (David Bradley) has been searching for the ancient book, the Occido Lumen, which could stop the Master and his army of strigoi. His search will come to an end in the finale, "Night Train," when he goes head-to-head with Eichorst (Richard Sammel) in a bidding war.

The synopsis for episode 13 reveals that Setrakian and Fet (Kevin Durand) will fight for possession of the book and they may get help from an unexpected person. Setrakian already knows he'll be getting help from Mr. Quinlan (Rupert Penry-Jones), so could this unexpected character be Eldritch Palmer (Jonathan Hyde)? Palmer was told by Eichorst he wasn't trusted, which is why the Master is sending Eichorst to go get the book instead of him. Could Palmer be bitter and turn on the Master even though the Master is the only reason he's alive? The person could also be Alonso Creem (Jamie Hector) who might finally start thinking about the greater good instead of the greater dollar amount.

Eph (Corey Stoll), Nora (Mia Maestro) and Zach (Max Charles) now have travel permits to leave the city and Eph will try to take Zach to his grandparents home in Georgia where he can be safe. First the trio will make a stop in Washington, D.C., to pick up supplies so Eph and Nora can continue to work on fine tuning their bioweapon. Leaving the city won't be easy for the three of them and they will face a massive attack when attempting to escape.

The bidding for the Lumen should be tense by itself, but it will be interesting to see what happens after it. At the conclusion of episode 12, Mr. Quinlan told Gus (Miguel Gomez) it was his job to take the Lumen from Setrakian and if he won't give it up, Gus must kill him. Gus likes Setrakian and they're all fighting on the same side, so will Gus have it in him to actually kill Setrakian if he has to?

In the promo video for the season finale, it looks like Kelly (Natalie Brown) returns and could be responsible for the attack on Eph, Nora and Zach. Setrakian swears they will get the Lumen or they will die trying to get, as their truck is shown getting blindsided by a big Mack truck. It's unclear who's in the truck, but an army of strigoi are shown storming the truck during the attack.

Prepare for what looks to be like an epic showdown between Mr. Quinlan and Eichorst in the final episode of Season 2. Eichorst declares that he fears no one, while Quinlan says, "neither do I" as he starts firing his guns at Eichorst. Several of the Season 2 plot lines will wrap up in the finale, but there will most likely be new ones introduced that will lead into Season 3 of "The Strain" next year.

Watch the promo video and see pictures from the season finale below:

“The Strain” Season 2 finale, "Night Train," will air on FX on Sunday, Oct. 4, at 10 p.m. EDT.