Angels of Terror (1971)

An Australian woman makes her way to London, determined to locate her missing sister. To her dismay, she discovers her sibling entangled with a dangerous heroin smuggling ring. As she delves deeper into the criminal underworld, a mysterious rival begins targeting the gang, systematically picking them off with deadly precision. With time running out, she must navigate a treacherous landscape of betrayal and violence in her quest to save her sister from a perilous fate.