Cornelia decides to go through with the abortion and turns to Cleary for help. Cleary's delighted to bring the daughter of the hospital's patron to Sister Harriet for her services. Harriet tries to convince Cornelia not to go through with it -- until it becomes clear that the child isn't her fiancé Phillip's.
Dr. Zinberg observes Thackery performing trephination on a patient with a brain tumor at the Knick. Barrow has invited him to perform a surgery there, much to Thackery's dismay. Zinberg mentions that he's currently working on identifying different blood types, a revolutionary idea. Thackery becomes obsessed with the idea of cracking it before Zinberg does. He devotes all of his time and resources to the research and sends Bertie to find out what Zinberg already knows. Zinberg is eager to share his notes with Bertie in the spirit of collaboration -- provided that's what Thackery is looking for.
Gallinger visits his wife Eleanor at the New Jersey state asylum. She is a shell of the woman she was and her teeth have been removed. Dr. Cotton, who believes mental illness is caused by sites of infection within the body, has pulled them out. He insists on removing all parts of the body that are prone to infection to stave off mental illness -- he's even done so to his own children as a preventative measure.
Collier interrupts Barrow when he's with Junia at the brothel. One of Collier's men roughs up the naked Barrow for missing a payment. An incensed and hurting Barrow asks Thackery to call in his debt with Ping Wu. He wants the Chinese gangster to kill his own debtor, but Thackery refuses. Barrow approaches Wu himself, pretending it's Thackery's wish that Collier be killed. Wu, dressed in battle attire, kills Collier and his men, and discovers the gangster's ledger. Now, Wu tells Barrow, he'll pay his debts to a new master.
Gallinger enters the hospital enraged and attacks Algernon. He's lost everything -- including Thackery's confidence -- and blames Algernon as the root cause.
Bertie returns from his meeting with Zinberg, but after seeing Thackery's state, he decides not to share the research papers. Thackery believes that each blood type is a distinct size. Bertie disagrees but Thackery insists on pursuing that line of thinking. He decides to test out his theory on a patient, a young anemic girl. He sets up a blood transfusion between himself and the girl. It fails and the girl dies. Thackery immediately realizes his theory's inaccuracy and his own unstable condition.
Cornelia and Phillip's wedding takes place. As they pledge their vows, Cornelia scans the crowd for Algernon but doesn't see him. Meanwhile, Algernon is drowning his sorrows at the bar and initiates a fight with a man he knows he can't beat.
The Knick board convenes to discuss the hospital's many problems. After a vote, they decide the best course of action is to move the hospital uptown.
After Thackery's failed experiment, Lucy rushes to find Bertie. They take in Thackery's sorry condition and Bertie finally realizes his hero is a coke fiend. They bring in Bertie's father who recommends a treatment facility to wean him off the drug. As they ride up together, Bertie reveals to Thackery that he wasn't even close with his research. The on-site doctors treat Thackery with a new wonder drug to help with his cocaine withdrawal. It's called Heroin.