The only accurate parts of this movie's title are "the" and "of"; there's no revenge, and there's no Dr. X. There is a rocket scientist though (I kept waiting for him to say "It's doesn't take a rocket scientist to [whatever]!", but he never did). He's on vacation in Japan, and he brought along a little box with something mysterious inside that he won't let anyone see. Now, those of us watching the movie already know that it's a Venus Flytrap because we saw him dig the thing up and put it in there, but nevertheless the "mystery" of what's in the box goes on for quite a while. I guess if a movie can't be interesting or entertaining, the least it can do is kill a lot of time. At any rate, eventually we find out that he wants to create the greatest Venus Flytrap the world has ever seen ("You will become the most powerful thing on this universe!"). It's all to prove some nutty theory about man evolving from the rutabaga or something, but obviously there's practical applications too. For example, he could sell them through ads placed in comic books:

Hell, if you can get a buck for a regular Venus Flytrap, think what he could charge for a Super Venus Flytrap. I'd imagine at least $1.29. So, there's tons more assing around while he gathers up all the shit he needs (oh well, at least some of this involves young, topless honeys), but eventually he's ready, at which point he hauls the fucking thing up to the roof so it can get hit by lightning Frankenstein style! Result: a goofy-looking plant man with Venus Flytraps for hands and feet! It looks like something that would fight Inframan. With nine minutes left in the movie the plant man finally goes on a boring rampage, so the scientist decides it has to be destroyed. After he tells his female assistant to "Stay!" he tracks the monster down and they both fall off a cliff. Into a volcano. The end. And thank fuck.