But Soylent Green is constantly in short supply and food riots are frequent. When one of Soylent's directors is murdered in what is thought to be a botched burglary, maverick detective Thorn (a wooden Charlton Heston) investigates. Learning that the victim's shifty bodyguard Tab Fielding (a wooden Chuck Connors) and companion Shirl (a wooden Leigh Taylor-Young) were away when the murder took place, Thorn is suspicious.

Before leaving the crime scene, Thorn steals the dead man's bourbon, apples and a cut of beef, as well as two reports concerning the state of the world's oceans. He passes the reports to friend Sol Roth (Edward G. Robinson, who, in his 101st and final film role, lifts the acting bar somewhat). Roth, who - due to his advanced age - can read, shares a cramped tenement flat with Thorn. The pair chow down on what for them is a slap-up feed.

Thorn's investigation leads him into a murky world where corrupt politics and big business collude. Roth, meanwhile, figures out Soylent Green can't be made from plankton because the oceans are dying. After discovering the grim secret of what goes into Soylent Green, he heads for one of the city's busy assisted-suicide parlours.

Arriving just in time to hear Roth's dying words and of his terrible discovery, Thorn secretly hitches a ride on the sanitation department truck disposing of Roth's body, soon to discover the horrific truth about dinner.

Although underwhelming the critics on its release and often dismissed since then as just another 1970s future exploitation flick, seems eerily prophetic in a way - many of the concerns that it expressed 40 years ago are now commonplace.