The unhappily married Alan and Liz narrowly avoid a traffic accident on their way home from the airport. Alan believes it was an attempt on his life by someone who knows he’s written a manuscript revealing the “alien presence” on Earth – perhaps the dreaded “men in black.”

Seth and Jane, an interracial couple, stop by to welcome Alan and Liz to the neighborhood. They’re curious about Alan’s atheistic beliefs and his claims of extraterrestrial visitors. The jovial but eccentric neighbors overstay their welcome and won’t leave, even when Alan demands it.

The neighbors give Alan and Liz exercises to improve their relationship. But that doesn’t address the more pressing issue of bizarre, poltergeist-like activity in their cabin, which began after the neighbors’ first visit.

Alan doesn’t believe in ghosts. He insists the paranormal events are due to the hitchhiker effect, a phenomenon that occurs when an individual comes in contact with aliens and is “followed home” by mysterious energies that inflict physical and psychological effects. The cause and solution to this problem are the subject of acrimonious debate between Alan and the neighbors. He struggles to maintain his sanity before ultimately concluding Seth and Jane are to blame for this disturbing predicament.