The plot follows a private detective, an ex communist and former CIA agent, who travels from Barcelona to Madrid to discover the identity of the assassin of the leader of the Spanish Communist party who was stabbed during a blackout while presiding over a meeting of the party's central committee. The film is a thriller with ironic political overtones.
After an old witch desecrates a church and abducts a baby, the police take her in for questioning, leading her to attempt suicide. To exact revenge, a fellow witch curses the police commissioner's daughter, and as the old witch dies, her spirit latches onto the young girl and causes her to wreak havoc.