The best network TV show that no one’s watching is ABC’s “American Crime.”

How this provocative drama from Oscar winner John Ridley got lost in the programming shuffle — and has yet to be renewed — is one of the more distressing mysteries of the TV season. Ideally, it should have premiered last fall, when audiences were primed for new offerings, instead of being tacked on the schedule in March — after the conclusion of the dopey (and unresolved) Viola Davis acting seminar “How To Get Away With Murder.”

Thematically challenging and structurally ambitious, “American Crime” offers something lacking in any other show on the ABC lineup: an actual adult story about an issue that affects us all — the nation’s criminal defense system. While Ridley’s point of view is very distinct, he skilfully dramatizes how one crime can ruin the lives of almost any family — and how the search for justice is, at the very least, frustrating and sometimes meaningless.

We meet the three families after the murder of Matt Skokie, a US military veteran who has become a petty drug dealer in Modesto, Calif. His divorced parents, recovering gambling addict father Russ (Timothy Hutton) and racist mother Barb (Felicity Huffman), are bitterly reunited. Matt’s wife, Gwen (Kira Pozehl), survives the shooting but is left stricken with aphasia and cannot help the case; her parents (W. Earl Brown and Penelope Ann Miller) are more concerned with their daughter’s recovery than with Barb’s crusade for justice. A local family, the Gutierrezes, becomes swept up in the arrests when a teenage boy (Johnny Ortiz) is in the wrong place at the wrong time.

The series, whose eighth episode airs next Thursday, kicks into high gear when the prime suspect, African-American drug addict Carter Nix (Elvis Nolasco), is released in the face of circumstantial evidence. Barb goes ballistic, flat-out telling the cops they don’t know how to do their jobs. She successfully campaigns to have the case reclassified as a hate crime and states her case on television. Not long after, a thrown brick shatters her car window. There is no witness to the crime and the cops can’t do much without one. Barb buys a gun for her own protection, gets a license and starts practicing on a firing range.

The demoralization of Barb is only one of the consequences of the original crime, but each is rendered powerfully. Ridley is greatly aided by a first-rate cast. After wallowing way too long in the silliness of “Desperate Housewives,” Huffman rebounds to striking effect as the intolerant Barb, a woman who will not back down from her crusade. Hutton does his best work in years as the wayward father who will never make up for lost time. Had “American Crime” premiered in September, the stars and supporting players, including Benito Martinez as Alonzo Gutierrez, would all be touted for Emmy consideration.