Trivia

Second part of a trilogy also including Paranoia (1969) and A Quiet Place to Kill (1970).

Riz Ortolani's theme here, "Why", was later recycled in Lenzi's " Seven Blood-Stained Orchids" (1972).

Carroll Baker's voice is dubbed by another actress in the English-language version.

Jean's car is a 1969 Pontiac Firebird Trans Am. The Trans Am package was introduced that year and cost an additional $1083. ($7643 equivalent 2020) to the original Firebird MSRP of $2942 ($19123 equivalent 2020).

The plot bears such similarity to the French classic "Les Diaboliques" that it has become known by the moniker "The Italian 'Diabolique'."