Ultrasonic tells the tale of Simon York, an aspiring musician with a beautiful wife and baby on the way. Ruth, Simon's wife, is supportive of Simon's dream, but their recent financial problems prove to be a strain on them. Simon begins to hear things that Ruth believes are just a result of his stress. Ruth's brother Jonas, an eccentric young conspiracy theorist, is the only person that seems to take Simon seriously. Simon's ailment leads the two of them into an obsession that spirals out of control and leaves everyone wondering, is it real?