The Facility (2012)

A research facility recruits volunteers to test a new drug, which is a crap shoot for anyone who volunteers. Since this is a horror movie, you know something is going to go horribly wrong.  The group of strangers are housed together in one wing of an isolated facility which has no other inhabitants.  They are forced to give up their cell phones and have no radio, TV or other electronic devices.

Since there is nothing to do except interact, we get some background info on each one as they converse.  Finally a movie in which the exposition is between strangers, rather than close friends who should already know everything that is being revealed.

The subjects are individually inoculated at regular intervals and each is scheduled for a series of shots. When the first volunteer has an adverse reaction to the injections, the rest of the group demands answers.  They are not comforted by the Doctors vague words and each fears they will have a similar reaction.

When the second person injected has a different, but equally bad reaction, the group panics and starts calculating when each person received their shot.  The thinking is that they watch whoever is going to potentially be affected next.  So if someone isn't affected, there's no way to know whether it's the person who received the placebo, or they are immune to the reaction.

The first thirty minutes of the movie are slow. It's British so that's not surprising. Then the action starts as people begin reacting badly to the drugs.  But then the movie starts to drag again near the end, so... meh.