Trust is a two way street and in horror movies. Our protagonists usually need all the friends they can muster, so why would anyone, especially a friend or trusted confidant, choose to screw over someone in need?
According to the movies, most betrayals happen for two reasons - love or money, or to put that another way, sex and power. There are some cracking examples of this in more conventional films; Commodus royally screws over Maximus in Gladiator, Cypher in The Matrix is a classic selfish rotten egg and there's Lando selling out out heroes in Empire but perhaps he should get a pass ("I had no choice, they arrived right before you did... ").
Betrayal does feature in horror, as you are about to read, but it's rarer than you may think. Our good guys are usually pitted against a monster, ghost or something more ethereal than your best mate stealing from you or seducing your partner.
Here though, the heroes are plunged into utter despair; lost in the woods with no way out, betrayed by the most trusted profession in the world (doctors) or committed to the padded cell by adulterous spouses. Luckily, these villains mostly get there comeuppance... mostly.
10. Guy, The Castevets, Dr. Sapirstein AND Dr. Hill Betray Rosemary - Rosemary's Baby (1968)
A LOT has been written about Rosemary's Baby over the last fifty-two years; it's an extraordinary film and deserves a place amongst the very best horrors of the last century.
Rosemary Woodhouse has everything she ever dreamed of; a stylish Manhattan apartment, a husband on the verge of getting his big acting break and the imminent patter of tiny feet. With a little help from her eccentric neighbours, the Castevets, everything is going to be perfect.
Except it isn't - she is now pregnant with the son of the Devil himself and is about to realise that nearly everyone she loved or trusted is actively conspiring against her. Her husband Guy has made a pact with the Satanist neighbours, the Castevets, to elevate his career and has placed her in the care of the evil Dr. Sapirstein. When she makes an attempt to flee, she contacts her original doctor, the good, kind Dr. Hill (Charles Grodin, who passed away this year).
"God bless Dr. Hill. Everything's gonna be okay now, Andy or Jenny. We're gonna be in a nice clean hospital with no visitors" says Rosemary, minutes before Guy and Sapirstein arrive to drag her back to the waking nightmare that has become her life.
It's hard to know who betrays Rosemary the worst but some betrayals are unintentional - Hill has no idea what he is condemning her to - but the realisation that there is no one left to help her cuts deep.