NOTE: This spoiler was submitted by Joshua.
The movie begins with Bradley Fine (Jude Law) infiltrating a black-tie party, with the guidance of Susan Cooper (Melissa McCarthy). He quickly makes it to the head honcho underground (Raad Rawi) and holds him at gun-point, who reveals himself as Tihomir Boyanov, the father of Raina Boyanov (Rose Byrne). He is about to sell a nuclear bomb to terrorists. Suddenly Fine's allergies act up and he sneezes as he shoots Boyanov's Father in the head. Susan is shocked, but she quickly leads him out as Fine escapes on a boat back to the CIA. It is EXTREMELY OBVIOUS that she has a thing for him.
Later, at dinner with Fine, Cooper receives a black box from Fine. She thinks it's a ring only to be shocked as it turns out to be a cupcake necklace. Fine then tells her to look at him closer---- only to find out that she contacted Pink-Eye.
The next day, at CIA Headquarters, Head Elaine Crocker (Allison Janney) briefs the agents on the mission at hand. Nobody knows where the nuclear bomb is except Raina Boyanov (Rose Byrne). She then sends off Fine to Boyanov's residence as Cooper is insulted and sent out by Agent Rick Ford (Jason Statham).
That night, before the mission, Cooper goes out with her best friend Nancy (Miranda Hart) at a bar. She says that she has no idea where she's going in life. She joined the CIA after she quit being a teacher and her husband left her, and she thought things would be better, but she's just the same old boring person she was. Nancy tries to cheer her up by insulting Agent Karen Walker (Morena Baccarin), but this back-fires when Walker notices them.
During the mission, Fine's cameras and tech are acting up at Boyanov's residence. Cooper tells him to back-off, but he goes inside and disarms both guards. Boyanov then suddenly appears and holds him at gun-point. To Cooper's horror, Boyanov shoots Fine in the head and exposes all the agents in the CIA.
The funeral for Fine happens, and Crocker decides to carry on the mission despite losing Fine. After confronting Cooper on calling Boyanov a thundercunt in the official report, Cooper discovers a list of numbers from Fine's spy-feed before he got killed. The numbers link them to De Luca (Bobby Cannavale), a businessman long suspected to be linked to terrorists; and who has an office in Paris. Crocker has no idea who to send (as all the agents' covers were blown), until Cooper volunteers, to the chagrin of Ford. After Crocker announces Cooper as officially on the case, Ford quits. Crocker then calls Cooper in her office and shows her a video from Cooper's training days. Cooper was the top of her class and was considerably aggressive, but placed herself in the job of analyst to the advice of Fine instead of being an agent.
Crocker then gives Cooper her first identity and sends her off to gather her gadgets and head to France.
Upon touching down in Paris, Cooper is brought, not to a grand hotel, but to a seedy motel. In her room, she is surprised by Ford, who has "gone rogue". After telling her a variety of (exaggerated) stories about his exploits, he tells Cooper to stay out of his way and that she would fail.
The next day, Cooper finds out that the office of De Luca was burned down- he knew the CIA was coming. She then spots one of his associates on a photo taken by a by-stander, and goes to a cafe where she is startled by Ford; who once again chastises her and walks away. Suddenly, De Luca's henchman appears and follows Ford. Cooper then follows them as an unidentified woman (Alicia Vela-Bailey) swaps Ford's backpack with an identical one containing a bomb. Cooper then chases and warns Ford in time for him to throw the bomb into the river without any casualties- but one of De Luca's goons snap a picture of Cooper- blowing her cover. Cooper chases him to the burned down office and loses him- until he appears behind her and threatens her with a knife. She then takes out her gun and threatens him to which he laughs- the bullets fell off. Cooper, however, successfully fends him off and knocks him off a balcony as he is impaled by rebar. A shaken Cooper then faints.
Back in her motel room, Cooper, who took the camera, sends the footage to CIA. They then hear De Luca talking about "Renaldo". They figure out that "Renaldo" is the name of a BMW car, and that it was presently in Rome. Cooper is then given another identity and flown off to Italy.
In Rome, a spy (Peter Serafinowicz) is sent to drive Cooper to intercept "Renaldo". Cooper then spots De Luca going inside the Casino. To go in, she buys herself a nice dress and makes herself up.
Inside the casino, Ford (Jason Statham) once again spots Cooper and insults her, while Cooper tells him to fuck off and that she's got this. Cooper then enters the private casino, and upon getting kicked out, she spots a waiter slip poison in a drink and alerts the customer- who is Reyna Boyanov (Rose Byrne) in the flesh. For her thanks, Reyna forces the waiter to drink the spiked drink- which burns a hole through his throat as Cooper faints in horror. Boyanov then takes Cooper out to dinner as thanks for saving her life.
During dinner, Boyanov spots Ford, sends her men to kill him; but Cooper sends out a morse code message to cut the power of the casino. While the power is out, she creates a diversion to let Ford go. Upon waking, Rayna brings "Penny Morgan" to her private plane en-route to Bulgaria, where Cooper is poisoned with her drink and knocked out.
Upon waking, Boyanov is confronted by the Pilot (Matt DeVere) at gun-point. Cooper quickly subdues him and the other hostiles, while getting the plane under control on auto-pilot. Boyanov then holds Cooper at gun-point, saying she knows she is from the CIA. Cooper then lies and makes up a fake name, saying that she's a bodyguard to protect her, and that her father sent her. Boyanov believes her and lets Cooper fly them into Bulgaria.
In Bulgaria, Boyanov's associate (Björn Gustafsson) meets up with her while Cooper, mistakingly believing him to be an assassin, throws her phone at his head and insults him all the way to Boyanov's room at the hotel. Upon being left alone, she turns on her ear-piece and makes her way out of the hotel, where Nancy (Miranda Hart) surprises her- she was sent to keep an eye on Cooper. Boyanov then spots them and after Cooper saying that Nancy is an assistant bodyguard, an unknown assailant shoots at them, killing Boyanov's associate. Cooper picks up a pizza delivery scooter and gives chase while Nancy runs with Boyanov. Upon catching up, Cooper is surprised to see that the assailant is none other than Agent Karen Walker (Morena Baccarin). Walker is then suddenly shot in the head by a sniper while Cooper flees.
Back at the hotel, Boyanov screams at her two incompetent "bodyguards", and tells them that her client is meeting her that night at a party, and that "don't fuck up if you don't want me to shoot a bullet in your heads". They then hire an "additional bodyguard" who is none other than the spy from Rome. At the party, Cooper spots Ford yet again, as well as the woman from Paris. She then follows her as Nancy attacks musical guest star 50 Cent (playing himself) on stage to get arrested and cause a distraction. Cooper follows the woman to a restaurant, where they fight, with Cooper overpowering her and accidentally launching a knife through her hand. As she arrests her under the FBI, someone launches a knife in her heart- Fine (Jude Law), who faked his death and is now with Boyanov.
Cooper is tied up and locked up with the spy from Italy. Fine then comes in and tells Cooper that his entire plan was to get close with Boyanov by faking his death, and that he was actually going to stop her. He tells Cooper to hang tight as he leaves, but Cooper has had enough. She gets help and frees herself and the spy from Italy as she drives to the estate of De Luca (Bobby Cannavale).
De Luca, who doesn't trust Fine, tells Boyanov that the deal is off unless Fine gets killed. Cooper then pops in and gives De Luca a deal- she'll allow the deal to happen if Fine lives. She then confesses about how shitty the CIA was and how she knew that Fine would never be hers. De Luca accepts Cooper's deal.
De Luca's customer then arrives and gives him his payment- millions of euros worth in diamonds. Boyanov then leads everyone to where the nuke is- inside "Renaldo" (the BMW) the whole time. De Luca then suddenly shoots his customer and holds everyone at gun-point. Ford once again interferes but accidentally knocks himself out.
De Luca runs while Cooper shoots and kills every one of his henchmen, with Fine getting shot in the process. Cooper then gives chase to De Luca escaping in his helicopter, with an awakened Ford chasing after them. Cooper catches on his helicopter while Ford grabs her boobs. De Luca tries to shake them off, but only succeeds on dropping Ford and Cooper's shoes. Cooper then swings herself inside the helicopter and throws the diamonds and the nuke in the lake below. An angered De Luca then attempts to kill Cooper, but Nancy, who is now on a helicopter with the help of 50 Cent, shoots him with a sniper and kills him. Cooper then lands the chopper- her first ever mission is complete.
Upon landing, Ford congratulates her and drives "off to sea" (which is now a nuke-contaminated lake), the spy from Italy is actually MI6 (and British!) and Fine asks Cooper out on a date. She declines to have a girls night with Nancy, and the two walk away as Cooper gets a new assignment.
Shortly before the credits roll, we see Cooper waking up in bed with Ford. She screams in disgust as Ford cuddles her and says, "I know you liked it".