A modern and unrelentingly tense psychological thriller based on a theory of the origins of shortwave radio frequencies, Shortwave is an unnerving reminder that some stones are best left unturned.

Martin, a drifter, arrives in a small town and asks about a woman named Ana. Peter, a teenager, directs him to a cemetery, but three thugs harass him. Peter interrupts them as they savagely beat Martin, but then flees. De Luca orders them cover up the crime. Peter convinces his mother, Monica, to perform first aid, which Martin refuses, saying that his blood is 'contagious'. When De Luca returns to bury the body and finds it missing, and suspects Peter. He sends Caleb to take care of the situation, but before they can kill Peter, Martin kills them. De Luca interrogates Peter. and sets Peter on fire. As Monica calls an ambulance, Martin recites a Latin blessing and rubs his blood on Peter. Later, at the hospital, Peter miraculously recovers and is discharged. The police capture Martin and make Monica, a nurse, perform a transfusion from Martin to Caleb. Martin begs her not to do so and insists that his blood must be blessed to prevent 'infection'.