Karen Brodine drops her nine-year-old son, Michael, at an arcade for a birthday party. A man claiming to be another dad offers her some punch; moments later she's passed out in the parking lot. When Karen comes to, the man, Karl Hoffman, has her strapped to an operating table. He patiently explains that he'll begin by collapsing her right lung, then move to breaking her collarbone. Later that night, Hoffman returns a barely breathing Karen to her car, barely alive, calls 911, says, "I've done it again," and walks away.
The next morning, Liz tells Tom that everyone at the Post Office is under mandatory surveillance until the mole is identified. Tom has news: he's hopping on a plane for a job interview in Nebraska - where life is normal. Stunned, Liz is about to react when she gets a text. The Good Samaritan Killer has struck again - Karen is dead. Liz was lead on the case at her last job... until the Good Samaritan disappeared. The case is personal to her, and she wants back on. Even after seven dead, she still doesn't know his trigger. The Good Samaritan never kills his victims and always calls 911, thus his moniker.
Furious about the Garrick incident, Fowler calls in OPR to interrogate all Post Office personnel. Haunted by visions of Luli's last moments on earth, Red is on a rampage, shaking down and killing anyone remotely connected with the attack on the Post Office. He's trying to follow the money to its source, but everyone was paid in cash left in constantly changing locations. After hearing about the return of the Good Samaritan Killer, Red calls Liz, knowing she's stumped. Perhaps the killer's methods have more to do with his victims than himself? After some investigation, Liz makes a discovery: Karen abused her son Michael, and the Good Samaritan treated her to the exact same injuries she inflicted upon her son. Maybe the same holds true for all the Good Samaritan's victims?
After brushing the hair of his mute, wheelchair-bound mother, Hoffman proceeds to work at a local ER. His patient, Melissa Wilkinson, has a broken wrist and has clearly suffered several injuries at the hands of her abusive husband, George, in the last year... nevertheless, she blames her own clumsiness.
Cooper tells Meera to bring in Aram, but Red has reached him first. Aram is going to make an untraceable $5 million deposit into one of Red's accounts in the time it takes Red to field strip and reassemble his gun, or he'll use the weapon on Aram. Terrified, Aram completes the transaction in the nick of time, satisfying Red that he's innocent of any connection to the Post Office breach. Someone else created the Louis Coogan alias to shift blame to Aram... and that someone is Kreuger. Red wastes no time shooting Kreuger in front of his wife, demanding a name. When Kreuger identifies Newton Phillips, Red takes his leave.
Hoffman joins George's 12-step domestic abuse program and tells his story. Growing up, he was a victim of his mother's "tough love," but now's he found a way to reconcile with her... It's not much later when Hoffman wheels his mother into the garage to introduce their latest guest: George. Apparently, Hoffman forces his mother to witness the brutal torture of all his victims so that everyone involved will never abuse another again. Back at the Post Office, Liz has cross-indexed all the Good Samaritan's victims to learn their one commonality: itinerant nurse Karl Hoffman was on call every time an abused family member was taken to the ER. In fairly short order, Liz figures that Hoffman is "schooling" his victims in his childhood home.
Finding Hoffman about to hammer George's skull, Liz shoots him in the gut. Later at the hospital, Liz looks in on George, promising that if he ever tries to hurt his wife again, she'll finish what Hoffman started. Meanwhile, Aram returns to the Post Office with a dossier Reddington gave him. Long story short, Red has identified the mole: it's Newton Phillips, aka the Man in the Grey Flannel Suit. After dispatching Luli's ashes into a river, Red suffocates Grey with a plastic bag, lamenting that he wishes things could have been different.
At a closed-door session of the ODNI, three suits grill Fowler, demanding to know the identity of her mole. She refuses, insisting it would threaten the identity of their anonymous asset (aka Red). Set for a Senate sub-committee meeting in minutes, Mr. Fitch is furious. What if Fowler's asset IS the threat?! Liz returns home expecting Tom, but it's Red who's standing in her living room. His house is now clean, but the FBI's is not - they have their own mole.
A serial killer from Liz's past strikes again while Red hunts for his betrayer. Alan Alda and Frank Whaley guest star.