Alien Beliefs

You know the story. The Nostromo lands on Archeron to check out the source of that strange emergency signal. The crew goes into the alien ship to examine it, and one of them -Kane, is infected by a parasitic idea.

The idea attaches itself to his mind in a most sinister way, by convincing him he cannot live a meaningful life without it.
The rest of the crew can only watch in horror as it consumes him, but initially they think it would be morally wrong to remove it, since Kane believes his life would be worthless and immoral without the idea.

Everything seems fine, but the idea morphes into a new stage of development. It bursts through the brain of Kane, and he is now determined to spread the idea to the rest of the crew.
This new form is a more violent meme which is extremely hard to kill. Its hosts gladly give their lives for it, as it makes them believe they wont truly die, but instead know eternal bliss in the presence of the idea. Moreover, when the idea is challenged and its fallacies are exposed, it protects itself by exclaiming that the one exposing its shortcomings will be tortured forever with acid.

As the crew tries to protect itself from the rampage of the idea, several of them are killed. Others are spared for the simple fact that they themselves has been implanted with the idea, and are reduced to living shells only kept alive to ensure the future of the notion.

Some events also show that some people in the government is fully aware of the idea, and that they are striving to get hold of it for their own purposes.

In their resistance against the deadly idea, one crew member stands out. It is Tracie Harris, an officer and call-in-show host. She arms herself with a logic-thrower, and with it she manages to defend herself against the advances of the idea, and finally escapes the doomed Nostromo.

As a consequence of this encounter, she dedicates her life to keep the the idea and the government separate forever.