It's a few years after the events of the movie THE FLY II. Seth Brundle's son, Martin, is now human, thanks to the teleportation device. However, he's feeling guilty over what happened to Anton, how he was transformed into a hideous fly creature. So he continues to experiment with the teleportation devices. In fact, he's been spending so much time at the lab that it's affecting his marriage to Beth, who just wants things to be "normal". That normal includes some kinky sex she wants to have on their anniversary.
Meanwhile, the last experiment with Anton caused a change-and he transforms into something much more dangerous, something that's contagious so that the whole facility has to be put into quarantine. The contagion, like the teleportation devices, start metamorphosing people into insect creatures.
This is a decent sequel that answers a lot of questions-and the artwork is suitably gloomy. Best of all the characters look exactly like the actors from THE FLY II (Eric Stoltz and Daphne Zuniga). Recommended.