If one were to evaluate the way science works in our culture using "The Outer Limits" as our guide, we would conclude that we stupidly launch headlong into whatever another alien culture wants and ask questions later. Henry Silva plays a convicted murderer who has been given the opportunity to participate in a major experiment. He volunteers to be sent to another planet through teleportation while the aliens send one of their own in exchange. The other guy comes first and he looks like a gigantic garlic with legs. He is allowed to roam around the compound. While there he spends lots of time at a pond where he throws things in the water. What develops is a living substance that he eats (actually he stuffs the substance in some part of his body). He is also quite dangerous when confronted, especially if his food source is threatened, and he manages to leave a couple of bodies in his wake. Meanwhile, Silva's prisoner becomes the center of things. It turns out the murder he committed was justified in his mind because the man had done horrible things to his sister. He develops a bond with a young female doctor at the facility who sees him in a much more positive light.
One thing. Watch the portrayal of the police in this episode. They are probably the most incompetent characters one has ever seen. When attacked, they throw their guns into the air and allow the threatening figure to get hold of them. The thing moves about two miles an hour and probably couldn't catch a one legged man. And it's not the element of surprise because they are out there looking for something dangerous. Just a sidelight.
There is one red herring in the plot as well (unless I missed something). A policeman, lying in the transportation device, disappears. Where did he go? No one mentions him. Also, there is critical denouement. Why did the aliens do what they did without using other means? Food for thought (no pun intended).