In the movie 'The Pacifier' what ever happens to Howard Plummer?

He is shot dead.

"Shane takes Plummer to a waiting chopper, where Plummer insists on calling his family. He opens up his briefcase by use of a voice-activated password: “Zoe, Seth, Lulu, Peter, Tyler”, revealing only a photo of his family, which he shows to Shane. As Shane goes aboard the helicopter to tell the pilot to wait for Plummer, only to find that the pilot is dead. Shane and Plummer are then shot by a barrage of gunfire, which only Shane survives."

https://en.wikipedia.org/wiki/The_Pacifier

I'm not normally a fan of Wikipedia, but in this case, it offers the best explanation.