A guy is being interviewed for a security job position at a jewelry store. He doesn't get the job and goes off grabbing some milk before he goes.
Murtaugh is playing basketball with Riana. He's out of breath and sweaty. He thinks Riana let him win. Trish wants to know why he's not at work. He wants to play another game with Riana, but Trish says no.
Avery is in a meeting with Dr. Cahill and Murtaugh. He wants to know where Riggs is. He tells them about the case of the jewelry guy named Chad Jackson. His background file sounds similar to Riggs. He was a Navy Seal. Sniper. Hair trigger reactions. It all sounds like Riggs. Riggs is outside walking on a roof ledge.
Dr. Cahill says he should check out the guy's psychiatrist. As Murtaugh is leaving he sees Riggs on the rooftop.
Murtaugh and Riggs are visiting the psychiatrist. Murtaugh asks a bunch of questions that fit with his relationship with Riggs. Riggs is sort of cocky and isn't thrilled with the doctor. Everything the doctor says about veterans hits close to home with Riggs. Murtaugh is picking up on it. The psychiatrist says if a vet doesn't get help, it could be very dangerous.
Jackson is at a pharmacy trying to get information on a pill. The pharmacist isn't helping because the bottle has no label. All he has is the pills. He's very agitated when the pharmacist doesn't know what the pill is. He beats up the security guard.
Murtaugh asks Riggs some questions while leaving the psychiatrists office, but Riggs doesn't really answer. Murtaugh is looking for answers about the military. He thinks Riggs would have more insight, but Riggs is just irritable. They get a call from Bailey about the pharmacy incident. They arrive at the scene.
Riggs wants to go in alone, but Murtaugh goes in with him. Cruz decides to follow even though he was told not to. Cruz really has an unspoken admiration for Riggs. Riggs is looking around for Jackson. He finds two empty milk bottles and Jackson sitting on the edge of the cold case.
Riggs starts talking military talk. They start talking and Jackson says he'll turn himself in once he's done with his mission. Riggs is trying to get to the bottom of it when Cruz makes a noise distracting Jackson, he runs, shooting. Riggs chases after him. Murtaugh tries to follow. Riggs follows him up a roof where Jackson jumps off and onto a truck then down onto the street and gets away.
Riggs is at his desk at the station when Dr. Cahill stops by. She asks for a drink. He talks to her a little bit about his experience in the war as it relates to the case.
Murtaugh visits Scorsese who tells him about the pill they got from the scene. It is similar to an anti-depressant for PTSD, but no specific drug on the market. He suggests it might be something off the streets.
Riggs is sharing information with Dr. Cahill. Apparently, Jackson's team members are dying here, and Dr. Cahill talks about drug clinical trials.
Murtaugh visits Trish at work to pick up paperwork to find out about the clinical trials. Trish is with her new assistant and is a bit jealous. He wants Trish to fire the guy because he's young and good looking. Trish just laughs it off.
Riggs and Murtaugh visit the pharmaceutical company. Riggs comments on the company pool. Patricia claims she can't discuss intellectual property. Riggs is not happy. Murtaugh wants to know if there are side effects. Murtaugh wants a list of all the other patients who took part in the trial. She tells them that Dr. Cox, the psychiatrist, provided them with the patients and administered the medication at his group therapy.
Cox didn't mention the trials so they call him. Instead of Cox answering, Scorsese does, because Cox is dead.
Riggs and Murtaugh are in Scorsese's area. He's telling them the doctor was shot in the head at close range. Avery shows up. Scorsese says Jackson's fingerprints were found everywhere. Avery wants to give a press conference, but Riggs isn't convinced that Jackson killed the doctor. He doesn't want Avery to do anything, because most of the men in Jackson's therapy group are dead. They all took the pills, apparently. Avery asks Murtaugh what he thinks and he says he thinks Riggs is too close to the case and agrees with Avery. Riggs not happy.
Avery holds a press conference. Bailey and Cruz are taking tip calls. One tipper mentions milk cartons and Murtaugh gets the information and they go to the area where Jackson might be.
They are hiking and Murtaugh is out of breath. They walk through the woods. Riggs tells him about his hunting experience. They step into Jackson's kill zone. He tells Murtaugh to go while he tries to talk to him. He just starts talking about experience while Jackson follows him with his sniper gun. Jackson speaks up saying he didn't kill Dr. Cox. He tried to get information from Cox. Riggs wants to take him in, but Jackson says he needs to finish his mission. Riggs offers to help, but Jackson declines.
Murtaugh is just walking around and steps on a booby trap bomb wire. he calls out for Riggs. Riggs comes to the rescue. Murtaugh is freaking out. Riggs saves Murtaugh by pushing him off the wire. The bomb blows up, but they are safe. Afterwards, Riggs wants to know who Desmond is.
It's early morning and Murtaugh is playing basketball. Trish wakes up when she hears him. He tells her about the day before. He's concerned that he lost a step. He says he hasn't felt like he hasn't been able to keep up since the heart attack. He's getting too old for this shit. He doesn't say it, but that's what he's thinking.
Riggs is in Avery's office. Avery is upset that Riggs didn't call for backup when they found out where Jackson was. Riggs defends the guy. Avery and Riggs have a fight and Avery pulls Riggs off the case.
Cruz and Bailey visit an explosive expert that Cruz knows. It's a former gang member. Cruz offers him a little bargain. They're trying to find out information about the bomb. He gives information that Jackson may be planning something bigger. Cruz finds Riggs and gives the information. Riggs at first isn't interested because he's off the case until Cruz tells him Jackson got enough C-4 to level a building. Cruz went to him first.
Riggs and Murtaugh end up at the pharmaceutical company. Riggs thinks his finishing the job by blowing up the building. Riggs and Murtaugh are stuck in an elevator when the power goes off. Jackson has a bomb strapped to him and is trying to calm the people leaving, telling them they have plenty of time.
Riggs and Murtaugh get out of the elevator. He tells Murtaugh they have to call for backup. Bailey tells Avery Riggs asked for backup and Avery wants everyone at the scene.
Riggs and Murtaugh end up in Patricia's office to get them out, but Jackson shows up. He's upset about the pills. Riggs tries to talk him down. Jackson gets shot by Patricia's security guy, just as he turns off the bomb, but the bullet hits the detonator. Riggs takes the bomb off Jackson. Murtaugh comes up with a plan and breaks the glass, takes the bomb and jumps out of the building with Riggs following. Riggs shoots the bomb and they both end up in the company pool.
Murtaugh playing basketball with Riana again while Trish watches. A great family moment.
Riggs shows up at the hospital where Jackson is. He tells Jackson the murder charges are being dropped. Dr. Cahill shows up, and he tells him to trust Dr. Cahill.
Bailey asks Cruz about Salazar. he shares information that they grew up in the same neighborhood.
Avery comes in to trying to find Riggs so he can apologize. Then he wants to know where Murtaugh is.
Riggs is on top of the roof drinking beer when Murtaugh shows up. He offers Murtaugh a beer. They talk a bit. Riggs shares some personal stuff about the war and returning home. then he talks about Miranda for the first time. Murtaugh tells Riggs he can talk to him. Murtaugh tries to take the beer away, but Riggs teases him. Murtaugh decides to sit on the ledge, but the opposite the way Riggs is sitting. It's a perfect bromantic moment.