Brian De Palma writes and directs this thriller starring John Travolta. Sound technician Jack Terry (Travolta) is out recording atmospheric noise for a low-budget horror film when he witnesses a car accident and abandons his recording to help the victims, a presidential hopeful and his escort Sally (Nancy Allen). With the politician dead at the scene, Jack escorts Sally to a nearby hospital. Back at his workshop, Jack listens closely to the tape and discovers evidence of a political conspiracy. Along with footage shot of the accident by fellow witness Manny Karp (Dennis Franz), Jack is convinced his recording captures an assassination attempt but his attempts to expose the truth are silenced at every turn. Meanwhile, Sally becomes the target of a Philadelphia serial killer as she too is drawn into Jack's investigation.