A chemist (Jack Kelly, FORBIDDEN PLANET) is working under the premise that all living organisms can heal themselves by adapting to harmful things in their environment. He has developed a serum that works on lab animals but it has never been tried on humans. When his colleague (Albert Dekker) informs him of a terminal case, they give the serum to the dying woman (Mari Blanchard). The result is miraculous and she is cured. But ... she has also been transformed into an evil femme fatale who will stop at nothing, including murder, to get what she wants. Based on the 1935 sci-fi short story THE ADAPTIVE ULTIMATE, this is a delicious slice of 1950s "B" movie pulp. Directed by Kurt Neumann (1958's THE FLY) and starring one of the best of the "B" movie brassy broads, Mari Blanchard, this is great fun. For a "B" movie, it's given the deluxe treatment, handsomely shot in B&W CinemaScope by Karl Struss (Murnau's SUNRISE). Alas, none of the rest of the bland cast is up to Blanchard's sassy histrionics. With John Archer, Fay Baker and Marie Blake (TV's THE ADDAMS FAMILY).