"Plutonium Is Forever" is the fifth episode of the first season of Scorpion. It aired on October 20, 2014.
Walter and his team try to prevent a decommissioned nuclear plant from melting down, aided by a former member of Scorpion.
A haggard man uses a compass to walk to an exact spot one mile outside of a Los Angeles nuclear reactor. When the helicopter and tank he was expecting arrive, he surrenders immediately, while demanding to talk to Walter O'Brien.
At Scorpion HQ, Paige struggles to get Ralph focused to leave for school as he's dazzled by the team's experiments. Cabe Gallo busts in to see Walter and asks what he knows about Mark Collins. Walter goes with Gallo to the base near the reactor, which has been decommissioned and is scheduled to be dismantled. Walter explains to General Walker that Mark used to work at Scorpion. He's an expert radio hacker. When Walter is taken to see Mark, he asks him if they're on solid ground. Mark assures him he's thinking clearly and is 100% sure there's a threat. Mark cites a lot of numbers and dates that make sense to Walter and refers him to his notes in his house, saying something big is coming. Walter wants to call in the team, but not tell them whose house they're going to. He tells Gallo the solid ground reference was just that Mark has always had the wrong idea about him. At Mark's house, the team sees the giant radio antennae in the backyard and figures out who lives there. They think Collins is nuts.
In Collins basement, Happy says the worst part of working with Mark was the way he got into Walter's head and erased his good judgment. They find the tape Collins mentioned and hear a scientist at the reactor talking about a necessary update and then blank audio. Collins has been checking the water and temperature levels and thinks there's a major problem being covered up. Walter announces they're taking the job to upgrade an ancient nuclear reactor.
Back at the reactor, Walter explains to General Walker that the reactor software is out of date. He quickly finds a bad fuse and discovers the plant is not within normal levels. The scientist on the tape moved out of town six weeks ago and essentially no one is monitoring the plant because its supposed to be cooling down. Walter estimates they have 18 hours before it gets overheated. Walter explains they need Collins based on his knowledge of the system gleaned from chatter. Outside, the team finishes telling Paige how dangerous Collins is for Walter. Collins was the closest in IQ to Walter, so he & Walter would go down the rabbit hole together. Working on projects, talking in code and going without food or sleep for days. Paige tries to talk to Walter about it, but he's not forthcoming. In the reactor, Collins tries to explain the several tasks they have. Before they get to work, Collins asks Walter if he wants to work on something else when they're done. Sylvester explains to Paige that Collins just disappeared and Walter wouldn't say what happened.
When it's time to get started, Happy wants to run a diagnostic test to make sure the system is up for the upgrade, but Collins thinks the diagnostic alone could stress out the system. Walter is forced to chose between them. He goes with Collins. Happy demands to talk to Walter outside, warning him never to go against her in front of everyone again or she'll bail. She reminds him how she saved him from his 10 day bender with Collins and nursed him back to health. She warns him if Collins stays, she's leaving.
Back inside, Happy decides to run a system check. Seconds later, alarms start going off as a generator blows. The plants starts to overheat and the team races to get on the other side of the containment doors. At the rate the temperature is rising, they're less than an hour from full meltdown. As the containment doors close, Walter and Gallo are trapped on the other side. Happy directs them to another door that's closing more slowly than the others. As they're running there, Gallo falls through a grate in the floor. Walter makes it through, but Gallo is trapped inside. When the team regroups in the control room, Collins immediately starts blaming Happy. And then a pipe blows, leaking radioactive steam into the room where Gallo is trapped. Walter knows Gallo will tell him to focus on the meltdown, not on saving him, but Walter suggests he and Collins together can solve both problems. Collins wants to go back to his house to look up information on a pipe Gallo might be able to climb out of.
Gallo demands to know more about Collins and Walter confesses that three years ago he had him committed to an asylum. At Collins house, he finds the tape he needs and directs Cabe to a pipe to get in and wash out to shore. As he prepares to jump in, Cabe tells Walter that if this is good-bye, he's glad he got to know him. Walter says OK. Cabe takes out a photo of his daughter and says he might be joining her soon. Moments later, he washes up on shore. Back at the reactor, they're programming a software update to stop the meltdown. At Mark's house, he tells Paige that Walter tossed him aside when he wouldn't follow his rules. He asks her how many times she hears I'm fine from him and warns him that she and her son might be Walter's next experiment.
At the reactor, Walter confesses to Gallo that part of why he had Collins committed was to see if he could be pulled from the place they used to get to where nothing existed but thought. Gallo points out that Collins has him questioning himself when he did nothing wrong. Walter has a thought and checks the computer log. He finds that Collins switched the system to manual update, knowing Happy would run a system check regardless and what he did would make her think she'd done something wrong. He wanted to show up the team and show his worth.
Walter announces they'll need antennas to override what Mark has done, but the base is too far away. They race to Mark's house to use his. At his house, they need his code to use the antennas, but he toys with Walter and won't give it to him, even as they approach 60 seconds from meltdown. As Collins says he just wanted to show that they needed him, Paige says the number they need is the date Collins was kicked off the team. Sylvester starts to type it in, and when Collins rushes him to stop him, Gallo shoots Collins in the leg.
Toby enters the code and they send the signal to update the software. The reactor immediately cools down. Back at the reactor, Collins has been patched up and Walter visits him. Collins wants to know why he would choose his team over him, and Walter tells him Paige is the difference this time. Back at Scorpion HQ, Paige comes by to make everyone stop working on their own projects and make dinner together. Paige pulls Walter aside to check that she's not on a tryout. She can handle the rejection, but she's worried about Ralph. He assures her she's one of them and they join the team making dinner.
- Elyes Gabel as Walter O'Brien
- Katharine McPhee as Paige Dineen
- Robert Patrick as Cabe Gallo
- Eddie Kaye Thomas as Toby Curtis
- Jadyn Wong as Happy Quinn
- Ari Stidham as Sylvester Dodd
- The name of this episode is a reference to the James Bond film and novel, Diamonds are Forever.