When "The Purge" franchise started, the annual lawless night of murder and violence was an established rite, one depicted again in two follow-up movies. Now comes the prequel, "The First Purge," which explores how the mayhem began.

The trailer introduces a doctor (Marisa Tomei) who's part of the New Founding Fathers of America (NFFA). They convince the country to run an experiment — 12 hours with no laws, including murder.

"If we want to save our country, we must release all our anger in one night," Tomei declares.

Despite protests against the idea, the Purge becomes a fact and so begins the first night of terror. And as in the other movies, innocent, fearful citizens find themselves hunted by roving gangs of killers.

At one point a reporter asks Tomei's character, "Is the Purge a political device?" Well, "The Purge" as a movie feels a bit like a political device. It certainly feels relevant in the current climate, particularly since the cast — including Y'Lan Noel, Lex Scott Davis, Joivan Wade, and Luna Lauren Velez — is predominantly African American.

"The First Purge" opens in theaters July 4.