The domineering FBI agent Sarah (Sandra Bullock) is always predictable and has made great achievements. However, her strong and lonely work attitude makes many colleagues unbearable. The complaints have once again hindered her promotion. Sarah's boss decided to send her to Boston and arranged a new partner Mullins (Melissa McCarthy) to jointly hunt down a Russian drug group. On the one hand, Sarah's wit will be brought into play, and on the other hand, it will test her ability to cooperate with others. However, this new partner is not a fuel-saving lamp, but a maverick and foul-mouthed female police officer in Boston. The two tough women who have never worked together began a hilarious running-in period, but their good show of working together to hunt down criminals has just begun...