A large oil rig gets boarded by a group of criminals, but something is a bit off on the rig. Most of the the crew seems to have vanished, and those still there are acting strange.
The 90's offered a sort of sci-fi horror genre with a very specific atmosphere, and that's exactly where "Proteus" comes in. Two of the other films were "Virus", and maybe more similar to the film in question, "Deep Rising". These films were all about a group of people boarding a ship of sorts, and it's also boarded by monsters. "Proteus" is just the same, except it's an oil rig. Yeah, the idea isn't from the 90's, and it's obvious in this film that the two biggest influences (or, well, source material) are "Alien" and "The Thing" (as always with the sci-fi horror genre). It's obvious in the way it's filmed, in the locations, in the paranoia among people and the fact that some people transform into the monsters. "Proteus" isn't aiming to be much more either, which is basically why it's a forgotten little film as well.
I really liked "Deep Rising", which came a few years after this one, when I originally saw it (and the re-watches around the same time as well). It was a fun, action-filled and interesting take of this genre, even though it fell into clichés and cheesiness at well. "Proteus" lacks most of what made "Deep Rising" so entertaining. This one is a stale story, with stale characters, with stale goals. More often than not they're looking for a missing person. It was impossible to care for anyone, and on a number of occasions I nodded off for a few seconds. It could be my medicine, but it could also be because the film is actually quite bad or at the very least boring.
"Deep Rising" did, however, have very bad CGI effects and that's where "Proteus" has the upper hand. The effects in this one are actually impressive and, more importantly, actually prosthetics. Sure, some cheesiness can be expected, and the finale with the huge mutated shark monster wasn't all that exciting. The monster itself looked way better than I had expected it to (think "The Thing" once again) but for some reason the big monsters at the end of films are often just there to look the part, they don't really do any harm. That's the case here as well, and that's always a let-down. Sometimes it works because the movie overall was so much fun, but in this one it's weak and another snooze-inducing ingredient. But yes, if you really like monster movies with fun prosthetic effects then I think it's worth to check this movie just for that reason.
I went into "Proteus" with low expectations, and knew that the only reason I wanted to see it was because it was a monster movie. It came off as a typical "Alien" and "The Thing" rip-off that fits in the same library as "Deep Rising" and "Virus". Except probably much more boring than both of those films. There's not enough excitement going on between the special effects, and it's always sad when that's all a movie has to offer. I loved the monster scenes but the movie overall didn't leave an impression on me at all, it's just boring and reminiscent of TV movies.