The story follows a young soldier named Johnny Rico and his exploits in the Mobile Infantry, a futuristic military unit. Rico's military career progresses from recruit, to non-commissioned officer, and finally to officer, against the backdrop of an interstellar war between mankind and an insectoid species known as Arachnids. It is based on Robert A. Heinlein's 1959 novel of the same name.

References:
https://en.wikipedia.org/wiki/Starship_Troopers_(film)