New York City is home to nine million residents and it's a bustling place, but the iconic 1973 sci-fi thriller Soylent Green posits a grim future where NYC has exploded to 40 million people and there's insufficient food and space for everyone. Unless, of course, you're rich and can afford to live in the protected community of the privileged, in which case you have every modern amenity, including a beautiful woman who comes as part of the "furniture".

The film revolves around the mysterious assassination of elite Soylent Corporation board member William Simonson (Joseph Cotten), and the subsequent investigation by NYPD Detective Thorn (Charlton Heston). Thorn shares a run-down, cramped tenement with his friend Sol Roth (Edward G. Robinson, in his last film role), a tired researcher who figures out that the widely consumed soylent green can't be made out of sea plankton because the oceans are dying.

Simonson's mistress Shirl (Leigh Taylor-Young) and bodyguard Tab Fielding (Chuck Connors) are both conveniently away when Simonson is murdered: does Fielding know more about the attack than he's letting on? Meanwhile Shirl grows fond of Thorn and lets him use the apartment, including offering him the experience of a shower with real hot water, an air conditioner that cools off "like winter used to be" and food in more abundance than he can ever remember seeing.

Soylent Green is primarily a warning of the dangers of overpopulation, but there's a thread of dystopic cynicism that still rings true, a mistrust of the motivations behind corporate activities and some equally striking commentary on religion and its Marxist function as the opiate of the masses, including when a beleagured priest (Lincoln Kilpatrick) explains to Thorn "we don't see no rich people at this church any more" and particularly late in the film when Roth is euthanized.

One of the most striking images in this film is when hundreds of people riot after being told that the government has run out of soylent green at a distribution center. Filmed with a yellow filter to give it an aged, gritty appearance, the scene is that much more shocking when crowd control turns out to be "Scoops", garbage trucks modified to pick up rioters and truck them away.

Symbolically, garbage trucks appear again later in the film in an even grimmer fashion, as Thorn hops aboard one to learn what happens to the body of his beloved friend Roth. With overtones of Nazi concentration camps, the solution to feeding the populace is grim indeed.

Dystopic sci-fi films can age poorly, but Soylent Green ranks up as one of the best films of the 1970's, a shocker with striking, upsetting imagery and a stark solution to the continued challenges of overpopulation. If you have a chance to see it, do so. It's well worth your time. Just skip any soylent foodstuffs your friends offer you afterwards.