Carlos, a business exec with a bum ticker, arrives home unexpectedly to find his heiress wife Alice (Erica Blanc) in bed with her lover Andrés (High Voltage's Juan Luis Galiardo) and nearly has a heart attack. When Alice, who owns the company, tells him she's leaving for good, Carlos slaps her senseless and entombs her in their rat-infested cellar. He suffers another attack a few days later when he goes down to the basement and finds Alice all chewed up by rats but still alive. That's when she rips off her mask and turns the tables on Carlos by burying him alive with the help of Andrés...
This is only the beginning of the nuttiness in yet another "bloodless" giallo that owes a huge debt to DIABOLIQUE. Ever-popular Eurobabe Erica Blanc is joined in the pulchritude department by platinum blonde Ágata Lys as Andrés vengeful ex-girlfriend. A couple of years later, Lys, a minor pop star, would make LA NUEVA MARILYN and get a lot of mileage in men's magazines posing as Monroe. Too plot-laden to have time for sex, THE DEADLY TRIANGLE lacks the erotic aspects generally present in any good giallo (save a coy "nude scene" for Erica) but that doesn't stop it from being enjoyable anyway, if only for the over-the-top antics.
