While protecting a man due to testify against the Morley cigarette company, Skinner is horrified when the witness dies mysteriously. What the agents soon discover is that a new brand of cigarette has a dangerous secret.

When a real estate agent is shot inside a prison cell by someone who apparently fired from the roof, Scully and Doggett track him to two exterminators, one of whom has x-ray vision.

Special Agent Reyes enlists Mulder's help in investigating a supernatural killer's connection to the unsolved murder of Agent Doggett's son, Luke.