If you loved The Boston Strangler, try Soylent Green
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Richard Fleischer, and they both carry the dread, paranoid mood tags, and they sit in Crime / Thriller territory. If that's the register that drew you to The Boston Strangler, the second film will land in a comparable space — through a different lens.
dreadparanoid
What Soylent Green is
New York City, sweltering summer, a worn clipboard. Overcrowding and pollution choke the streets, a synthetic food source is the solution. This bleak vision of 2022 is a hallmark of 70s science fiction.

