While hedging for a promotion, the prudish FBI Special Agent from New York, Sarah Ashburn (Sandra Bullock), a methodical investigator with a reputation for showmanship and arrogance, is forced to partner Boston street-level officer Shannon Mullins (Melisa McCarthy) to track down a drug lord before his next big shipment comes in.
What keeps you amused is to see how the straight-laced Ashburn deals with a foul-mouthed, uncouth Mullins, especially when they start off on the wrong foot.
What follows is that Ashburn gets a directive to allow Mullins' involvement in her case and neither is initially pleased.