CBS’s “Limitless” spinoff had yet another crossover with the film’s principal character as episode 6 merited the return of Bradley Cooper as Sen. Ed Morra. As the side effects from the superdrug NZT become clear, Morra offers a seemingly impossible ultimatum. 

The episode opens where things left off last week, with Brian Finch (Jake McDorman) revealing to his friend at the FBI, Rebecca Harris (Jennifer Carpenter), that he’d stolen valuable files from her boss, Naz (Mary Elizabeth Mastrantonio). They have evidence indicating her deceased father had a relationship to NZT prior to his death. She’s confused about why he committed high treason just to be a nice guy to her, but her desire to figure out what happened to her dad trumps the idea of an arrest. They agree to work together to figure out what happened, and why the FBI kept the information from her.

A note scribbled in the margins of one of the documents leads them to a rehab facility that her dad did a stretch in prior to his death. They’re about to go check it out when Naz approaches Harris with a phenomenal career opportunity. Naz has been selected to act as a cyberterrorist group leader, determined to launch an attack on the U.S. economy as part of an inter-departmental training exercise. Believing her relationship with Harris to be business as usual, she offers her a chance to help out and boost her standing at the bureau. Reluctantly, Harris agrees so as not to blow her cover. This means Brian has to go off to investigate the rehab center all by himself. 

While he’s there, he gets a ton of files, but his victory is short-lived. As soon as he steps outside, he starts to experience the familiar side effects of NZT withdrawal. Previously, Morra had inoculated him with an antidote he developed that allows someone to use the drug without worrying about its fatal side effects. His associate, Mr. Sands (Colin Salmon), promised Finch that he’d give him a booster shot of the formula if he stole the aforementioned files, but has yet to make good on his end of the bargain. Finch calls a meeting with Sands, but the nefarious villain changes the deal. He tells Finch that his relationship with Harris is causing Morra to worry that the FBI may get too close to discovering the true secret of NZT. As a result, he tells Brian that he’s going to make him suffer from withdrawal unless he finds a way to get Harris out of the picture -- like framing her for stealing the files.

With the clock ticking before Finch’s addiction kills him, he keeps taking the drug in the hopes that his super-brain will help him find a way out of the situation. Meanwhile, Harris shows up at Finch’s place after absolutely crushing it during her first meeting with Naz and her team. Unable to mention anything about his Morra troubles, he starts to show Harris what he gathered from the rehab facility. 

It turns out that her father and four other patients were meeting with a man named Andrew Epperly regularly and, when they all got out, they miraculously turned their lives around and became wildly successful people. It turns out Epperly works for a pharmaceutical company called Ubient that Finch believes may have created the superdrug. Hoping to find a way to reverse its side effects without ruining Harris’ life, Finch chases the lead pretty hard. 

Meanwhile, as his condition begins to deteriorate, Finch hatches a plan to go over Sands’ head and contact Morra directly. He steals the cellphone of one of his personal assistants and texts him asking for a meet. Morra tells him he’ll be in touch.

While waiting, Finch goes to Ubient to speak to its executives, but they genuinely have no idea what NZT is or what Epperly was really up to. Unfortunately, Epperly is dead now so the trail is cold. As he’s leaving the office, a bold woman from the company sneaks outside and tells him that Epperly faked his death and is currently living in Connecticut. Realizing that the withdrawal symptoms are getting to be too much, he calls Harris to give her all the information he’s gathered about Epperly and implores her to go see if he can reverse the drug’s side effects. His timing couldn’t be worse as Harris was just being told by Naz that her efforts on the cyberattack exercise were so good they impressed the director of the FBI. He’s gone as far as to ask her to meet him in Washington, D.C., the next day. 

Torn between her secret mission with Finch and her career, Harris makes the tough call to skip the meeting and go to check out Epperly. She finds him hiding out in a remote part of the state after he noticed a pattern during his medical trials with NZT. He says that he got an anonymous e-mail with the drug’s formula and, once it got a bit more widespread around New York City, everyone who was affiliated with it started to disappear or die, including her father. That’s when he drops the real bomb: He has no idea how to stop the side effects of NZT.

Limitless "Limitless" characters Ed Morra (Bradley Cooper, left) and Brian Finch (Jake McDorman, right) reunite in episode 6 of the CBS series. Photo: CBS

Just when it looks like Finch is going to die, he wakes up on a rooftop to find his white knight, Ed Morra, has saved him. He gets the booster shot he needed as well as five free NZT pills. It is of little consolation to Finch, who still sees Morra as the type of guy who would threaten his family and friends to get what he wants. Morra reveals that he never actually expected Finch to get rid of Rebecca and that it was all an elaborate test to see if he was the type of person who would cower to orders or use his NZT prowess to focus on the greater good. Morra seems to have big plans for the world, thanks to his genius and resources, but says he needs partners like Finch to help. Just like that, Finch’s reservations about his new employer are washed away as he gets to keep using NZT and work with Harris consequence-free. 

Unfortunately, this is of little consequence to Harris, who gets a call from Naz about missing the meeting and fully expects to be fired. Instead, Naz explains that she’s figured out that Harris knows about her father. She’s mad, but makes it clear that Harris’ family relationship to NZT is not what got her the job. Naz says she always saw promise in the young agent and, to prove it, took responsibility for her missing the meeting. This offered Harris another shot to go to D.C., which means her career is saved.

Just when it looked like all the good guys would be winning this time around, the episode cuts back to Epperly’s secluded hideaway. Sand drops off a package that turns out to be a bomb. The explosion presumably kills Epperly -- and their last remaining connection to the case of Harris’ missing father.