One idea I had back when I was a teenager and it was airing:
The crew rescue a man who is participating in a galaxy-wide game of assassin with some significantly large prize. The man, however, no longer wants to participate. He wants to leave and go home. The way it ends is, Voyager protects him for a while and helps broker an agreement to allow people to forfeit the game without being killed. But it turns out the guy they were protecting was conning them and uses Voyager to try to eliminate all the other players.