Natasha Belenko is a Russian immigrant, and a witness to a murder assigned to be protected by Riggs and Murtaugh. She is two months pregnant with her unborn child. Something about that of Natasha reminds Riggs of his deceased wife who was pregnant at the time.
Natasha worries in that she may be targeted after witnessing a murder at a pool party, which Riggs and Murtaugh are currently investigating. Just where she was about to be asked questions about the murder, she takes to the roof in fearing that she'd be found out about telling about it to the cops. Right where she was about to reveal it to Riggs and almost get shot, Murtaugh shoots up at the assassin and Riggs notices and he jumps off the roof with her and into the window of a residential apartment.
Later at the station, Riggs and Murtaugh ask her about the murder she witnessed. She tells them everything about it, but still fears that she may get found out in telling them everything she saw. Riggs promises her she'll be put into Witness Protection and will then testify thereafter.
Meanwhile, Riggs and Murtaugh are connecting the murder Natasha witnessed to an illegal arms dealing of government weapons. After Riggs found out that Bennet Hirsch, a crooked ATF agent, was in charge of the illegal arms dealing, he had the vaguest suspicion that Hirsch also found out about Natasha witnessing the murder and would be going after her. Riggs and Murtaugh then go to the warehouse where the deal was taking place between Hirsch and Jack Kirstein. Right when Natasha was about to be killed, Riggs and Murtaugh engage in the gunfight with Hirsch and the rest of the bad guys there. Riggs gets Natasha to safety and gives Murtaugh the advice to shoot the truck. The gunshot sparked the fireworks and lit up all the other explosives in there. Right where Hirsch was about to make the getaway, he gets sparked and burnt by the fireworks and the explosives. There, Riggs, Murtaugh, and Natasha all escape the warehouse, the warehouse then explodes, taking Hirsch with it.
Natasha thanks Riggs and Murtaugh for saving her, she is then brought in by the Witness Protection Program to testify.