Plot.
Lorna Cole is pregnant with LAPD Sergeant Martin Riggs’ baby; they are not married, but both are thinking about it. LAPD Sergeant Roger Murtaugh’s daughter Rianne, is also pregnant. Due to issues with the department’s insurance carrier over Riggs and Murtaugh’s actions as sergeants, the Police Chief has Captain Murphy promote them to captains. The officers along with Leo Getz come upon a Chinese immigrant smuggling ring after running an ocean-going vessel aground, though the captain of the boat escapes. In the subsequent investigation, Murtaugh finds Hong and his family hiding from US Immigration officers to avoid deportation. Murtaugh offers them shelter in his home, and their families, along with Riggs and Cole, quickly bond. Hong reveals he is looking for his uncle, a skilled engraver, who had paid for their passage to the United States. Riggs discovers through Lorna that Murtaugh’s yet-to-be-born grandchild from Rianne is by Detective Lee Butters, which Murtaugh cannot possibly tolerate as he did not want his daughter to marry a police officer, and that Murtaugh still does not know who the father is due to the family hiding it from him. Continued investigation of the smuggling ring leads the officers to “Uncle” Benny Chan, a crime boss operating from a Chinatown restaurant.