Hammer House of Horror (1980)

S1E10 Guardian of the Abyss

Australian antique dealer Laura Stephens acquires an old mirror as part of a job lot at an auction. While examining it with her colleague Mike Roberts, they are approached by the menacing Simon Andrews, who makes a tempting offer for the mirror, which Laura declines. On their way home, Mike encounters a runaway named Alison, who claims to have fled from the dangerous Choronzan Society. As they talk, she reveals that the mirror is a 'scrying glass,' thrusting Mike into a dark realm of human sacrifice and devil worship.