Garden of the Dead  (1972)

Theatrical Release Information:
Garden of the Dead

This plodding, low-budget zombie film is set in a maximum-security prison, wherein a group of convicts "just say yes" to a combination of chloroform and formaldehyde, triggering a fit of uncontrolled rage. In the subsequent riot, the crazed cons are all shot dead by the brutal guards, but remain so well-preserved that they manage to rise up from their mass grave to seek the blood of their tormentors -- including the warden -- armed with a variety of sharp implements from the prison toolshed. Dreary and uninvolving stuff, from the director of the more interesting Grave of the Vampire. Also released as Tomb of the Undead. ~ Cavett Binion, All Movie Guide