SPOILERS SPOILERS SPOILERS
Scientists at a Berkeley, CA university were given a grant to research cataracts in dogs. Along the way of research - as one thing leads to another, and “brilliance” has a break through - that dog research turns into creating a serum that brings back the dead. As one scientist puts it: To help health care and its patients. The serum will help once dead patients recover from any brain damage and long term effects. It is a scientific and medical breakthrough. The scientists experiment with pigs and dogs. All fail. Then one day, wallah. It works, after one of the associate scientists proposes a solution to alternate the serum.
The relationships between the scientists are a cliche. The two leads are in a relationship, Zoe and Frank, engaged actually - for three years. The timing of the proposal happened shortly before the grant was issued. Frank is too wrapped up to set the date of the wedding, and Zoe is waiting in heart break. The associate scientists, Clay and Niko, are two young associates. Niko has feelings for Zoe, but she’s taken. Clay is the “laid back guy who smokes” yet has moments of brilliance (the scientist who made the serum work). Enter young college student Eva. She’s brought in to tape the experiments, to tape the attempts to bring the dead back to life. Later in the movie it is revealed, in a very harsh way, that she yearns to be “part of the group,” “one of them.” But she’s not a scientist, as Zoe reminds her.
After a few days at the lab, wallah, the serum worked on a dog who later exhibits odd characteristics - no sleep, no appetite, slow growth of aggression. Clay warns Frank about the increase brain activity, but he shrugs them off saying that it’ll decrease within the week. It doesn’t.
As the week goes on, Zoe is suffering from nightmares. Within this nightmare there is a young girl standing in a hallway in her pajamas; she is holding something but it isn’t revealed. She is standing about 30 feet away from a door with muffled noise coming from it. We then learn that the people behind the door are trapped, as light - fire - engulfs the hallway that the young girl stands in. Burnt hands suddenly reaches out underneath the door. She wakes up. The camera then cuts to Zoe, in real life, dangling a necklace – at the end of the necklace there is a crucifix. Frank - later in the movie - admits that Zoe is a Catholic.
Next day. Daytime. During down time in the lab, Zoe and Frank get into a discussion about the research they’re doing, initiated by Eva. It is heavily implied that Frank believes in science, not in God; he is an atheist. The talk carries into the brain activity when a person dies - their brain is flushed with a chemical called DMT (
en.wikipedia.org/wiki/N,N-Dimethyltryptamine ). DMT, according to Frank, is the reason why people see “the light at the end of the tunnel.” The “light” is just an effect of the DMT - the “highest high” according to Frank. Zoe doesn’t necessarily disagree. As a scientist she acknowledges the effect, but she thinks it doesn’t entirely describe “the light at the end of the tunnel”; she thinks it’s a doorway to a greater plain - heaven. Frank clearly is irritated.