When I watched this two-part episode of "The Outer Limits", I had no idea that it was a two-parter. Instead, I accidentally watched the second episode--because the DVD had part one and part two on different sides of the disc. Oddly, however, part two alone made for one of the greatest episodes in the series!
Everything in part one was explained or alluded to in part two. What you see in part one is mostly about the Lieutenant--his injury, the surgery, the beginnings of his odd psychic powers, etc.--but there is also much more emphasis on the work of the government investigator (Robert Duvall) and his tracking down the cause of the strange changes in four soldiers all shot in a place which seems to probably be Vietnam (though the country is left unnamed). Regardless, four soldiers have brain injuries from weird bullets and the four find themselves being compelled to work on some strange other-worldy project--and the government is very worried about what this project may be. I'd say more, but it would spoil the suspense.
It's all very interesting but also seemed a bit stretched thin--like the episode could have been done in 30 minutes. Still, it's all very interesting and along with its conclusion make for great viewing. Well worth seeing--and very intelligently written.