A cure may have been found for the plague taking over New York City on FX’s “The Strain.” While it seemed like hope was running out, Eph (Corey Stoll) and Nora (Mia Maestro) had a breakthrough with their test subject Harrison McGeever (Ron Lea) in episode 4, “The Silver Angel.”

With Creedence Clearwater Revival’s “Fortunate Son” playing in the background of the van, Eph cuts McGeever loose. He finds his way to a psychiatric ward filled with sleeping strigoi. McGeever, who was infected with the virus Eph and Nora developed to fight the spreading of the plague, lays down next to strigoi and the virus spreads to the strigoi by contact.

Eph and Nora return to the hospital the following night, only to find strigoi launching themselves off the top of a roof. It appears the Master caught wind of what they had done, and to avoid the strigoi from spreading the new virus further, had them all commit suicide.

With this discovery, Eph feels it’s time to use their new virus to implement an attack on the strigoi. He plans a trip to Washington DC to show an old friend his findings so they can try use it as a weapon to stop the spread of the strain.

Zach (Ben Hyland) continues to struggle with missing his mother Kelly (Natalie Brown), while Eph tries to have some father-son batting time at the vacant batting cages. But all it did was stir up memories for Zach when they were one big happy family.

Zach may have a reunion with his mother sooner than later, as the episode came to a close with Kelly and his army of feelers tracking Zach. They get a major lead after catching his scent at the batting cages.

After an unsuccessful mission of kidnapping Eldritch Palmer (Jonathan Hyde) in episode 3, Gus (Miguel Gomez) returns home to pick up some more clothes. Unfortunately he came across his mother, who is now a strigoi. The Master takes over her body, telling Gus that the ancients he’s working for are the past and that he’s the present. He adds that he can still feel Gus’s mother’s disappoint for him. Gus doesn’t take the bait to kill the strigoi form of his mother and instead leaves the apartment.

A new character emerges in the opening scene of episode 4, as viewers were introduced to Angel Guzman Hurtado (Joaquín Cosio), an old lucha libre wrestler who was watching old VHS tapes on his glory days when he starred in movies. He was appropriately watching Angel vs. the Vampire on his break from washing dishes at a restaurant.

Gus and Angel cross paths after Gus comes to the restaurant twice, but Angel suspects that Gus is bad news and doesn’t like how the waitress Aanya Gupta (Parveen Kaur) seems to like Gus.

We later learn that Angel was once known as “The Silver Angel,” but his career came to an end after a knee injury. With the fate of Vaun (Stephen McHattie) still unknown after episode 3, it appears Gus may have found a new partner to fight vampires with.

Dutch (Ruta Gedmintas) and Dr. Abraham Setrakian (David Bradley) head out to Staten Island in search of Eldritch Palmer’s (Jonathan Hyde) former head of security, Mr. Fitzwilliam (Roger R. Cross). They find him at his brother’s firehouse where they ask him to join their team and help them take down Palmer and the Master.

Fitzwilliam’s declines the offer, but Setrakian leaves him with a card on where he can find them. He also adds that Fitzwilliam’s made the choice to not support Palmer after he walked away from his job.

Fet (Kevin Durand) decides to continue his mission of taking back Brooklyn and cuts off the main strigoi route to Red Hook by blowing up the subway tunnel. Unfortunately he runs into some of Councilwoman Feraldo's (Samantha Mathis) security and is arrested even though they are both on the same side.

Episode 4 also saw another flashback in Setrakian’s past at the University of Vienna in 1966. Setrakian and Palmer were searching for the Occido Lumen , the book that could help defeat the Master and the strigoi. This leads them to Berndorf, Austria where Setrakian believes a Hungarian disguised as a Christian was holding it. They arrive and find that they are too late -- the book had been destroyed.

The scene also shed light on how Palmer and Eichorst (Richard Sammel) first came in contact. Eichorst, knowing Palmer’s want for immortality, uses this to his advantage to bring him on his side. After fighting off strigoi in the chapels and saving a boy, Setrakian returns to Palmer who just simply wants to return to New York and not help Setrakian rid the world of the evil.

In present day, Palmer continued to carry out his work for the master as Bolivar (Jack Kesy) and other strigoi attack some of the city’s key financial players who were planning on opening up trade again in the city. However, they were ambushed after leaving the Financial Reserve building after Palmer set them up.