City of Fear (1959)

Vicious drug dealer Vince Ryker escapes from San Quentin with another prisoner after stabbing a guard to death and stealing what he believes to be a cannister filled with experimental heroin from the prison hospital. In reality the container is filled with cobalt-60, a highly radioactive substance which threatens the entire city if it is somehow opened. The ruthless Ryker dumps his dying cellmate and murders a bypassing motorist, burning his body beyond recognition. Assuming a new identity, Ryker heads for Los Angeles to become reunited with his beautiful girlfriend and Crown, a corrupt businessman and front man for Ryker's drug business. Fully aware of the potential dangers of the situation, the authorities are engaged in race against time to recover the cannister and avoid citywide panic.