Watched this little gem on Netflix a few nights ago. It's low-budget sci-fi, of course, but it's well done low-budget sci-fi.
A team of four Navy Seals are sent by one government agency to another government agency's black site to see what's going on there. All of a sudden all communication and travel from the site stopped. Mission: find out what the work was and rescue anyone who needs rescuing.
After a bit of character development, the team goes in and finds one surviving scientist and a strange object of unknown origin. A short time later, four alien soldiers show up and start forcing their way into the building. A decent amount of suspense ensues as the Seals try to figure out a way to combat their technologically superior opponents and figure out what they want.
I suppose the story is derivative of a few other things, but they make it work pretty well, and the acting and direction aren't bad at all.