Inspired by the crime spree of the psychopathic murderer Billy Cook (1928–1952), the screenplay was written by Robert L. Joseph, Lupino, and her former husband Collier Young, based on a story by blacklisted Out of the Past screenwriter Daniel Mainwaring (who did not receive screen credit).
Terinspirasi oleh kejahatan berantai dari pembunuh psikopatik Billy Cook (1928–1952), skenarionya ditulis oleh Robert L. Joseph, Lupino, and her husband Collier Young, berdasarkan pada sebuah cerita karya penulis Out of the Past yang masuk daftar hitam Daniel Mainwaring (yang tak dicantumkan dalam kredit layar lebar).