FX’s “The Strain” premiered an exciting episode in Season 3 last week in which Councilwoman Justine Feraldo was attacked by strigoi bombs. Elsewhere, The Master communicated with Eph through an average strigoi that he still has his son Zack. But the best aspect of episode 4 was seeing Quinlan alive.

Episode 5, which will air on Sunday, will see Eph (Corey Stoll) go back to the laboratory and try to understand how The Master communicates with them through his army of bloodsuckers. The synopsis (via SpoilerTV) states that the doctor will conduct experiments on strigois in order to understand The Master’s communication channel. However, his experiments will take him to the brink of madness.

Watch the promo of “Madness” below:

“The Strain” Season 3, episode 5 will also depict Feraldo’s (Samantha Mathis) desperation in killing strigois and ridding New York of the bloodsuckers. After more than 60 staff members were infected with worms last week, the Councilwoman begs Eph to create a potent bioweapon. Time is running out.

Meanwhile, rat exterminator Fet (Kevin Durand) embarks on a mission to discover strigoi movements across New York City. However, his mission will lead him to stumble into tunnels filled with thousands of The Master’s servants.

While things look bad for Fet and Feraldo, a new alliance may help take down The Master. Setrakian (David Bradley) gets new information about the mysterious Occido Lumen which forces him to seek help from a life-long enemy – Stoneheart CEO Eldritch Palmer (Johnathan Hyde). Palmer had previously offered Setrakian a deal to work together to take down The Master and Eichhorst (Richard Sammel), but he refused to shake hands with a nemesis and traitor. A discovery will certainly change his mind.

Hopefully, the upcoming episode on “The Strain” Season 3 will reveal The Master’s new vessel. Speculation suggests that it may be Eph’s son Zack (Max Charles).

“The Strain” Season 3, episode 5 airs Sunday, Sept. 25 at 10 p.m. EDT on FX.

The Strain What will happen in “The Strain” Season 3, episode 5? Don’t miss the episode on Sunday, Sept. 25 at 10 p.m. EDT on FX. Photo: Michael Gibson/FX