One of the first of several horror films with "Don't" leading the title, this gory low-budget thriller takes place in an experimental hospital for the criminally insane, where the pioneering director allows several patients to act out their twisted fantasies (which involve necrophilia, paranoia and popsicles). When a new staffer shows up, things start to go haywire -- beginning with the bloody axe-murder of the doctor himself and leading to a total takeover of the asylum by its most dangerous inmates. The acting is horrendous, the sound is incoherent and the color is so cheap-looking that some theaters were issued black-and-white prints... but somehow the intrinsic sleaziness generated by the threadbare production manages to lend it a remarkably suitable ambience. Instead of vanishing into obscurity, this quirky little potboiler became a staple on the early-70's drive-in circuit, thanks to Hallmark Films' frequent double-bill bookings with Wes Craven's Last House on the Left (even borrowing the logline "Keep telling yourself: It's only a movie...") and Mario Bava's Bay of Blood. Some video versions are missing most of the graphic violence from the original cut.