Greg Kelley was a high school football star in Texas, and when you're in high school in Texas, life doesn't get much better.

Then one day in July 2013, a 4-year-old boy said he had been sexually assaulted by "Greg," and Kelley was suddenly recast as a child molester.

The question, of course, is whether Kelley really did molest the boy, and a five-part documentary called Outcry, which premieres at 10 p.m. ET Sunday on Showtime, examines how the justice system did not come to the same conclusion as many of Kelley's friends and others in the Leander community.

Kelley was convicted, largely on the testimony of the boy, and sentenced to 25 years without the possibility of parole.

He went into prison protesting his innocence, and he became one of the relative handful of convicts whose case was kept alive by investigations outside the justice system.

Kelley's 25-year sentence was the minimum for the crime with which he was charged – aggravated sexual assault of a minor – and to avoid a potentially much longer sentence he had agreed not to appeal the verdict.

Soon thereafter, however, suspicious factors began to emerge, involving the police, the prosecution, and the lawyer who had represented Kelley.

That lawyer, Patricia Cummings, had been recommended to Kelley by the woman in whose home Kelley had been planning to live for his senior year at Leander High. His own parents had medical and other problems, and Kelley wanted to stay in Leander for his senior year before leaving for college the next year on a football scholarship he had already accepted.

The woman with whom Kelley had moved in, Shama McCarty, had a son, Johnathan, who was one of Kelley's best friends. Kelley recalled Shama as a big football booster and a supportive mother figure.

Over the next couple of years, though, things emerge, suggesting there may have been some grey areas involving McCarty's intentions and actions.

A case involving the molestation of a preschool boy inherently becomes emotionally charged, and a fair number of people in the area were convinced Kelley had done it and deserved the worst punishment available.

They were allied against those who agreed the molestation was terrible but insisted Kelley wasn't the perpetrator.

Then, and this becomes a tricky element in almost all such cases, there's the question of how to weigh the words of a 4-year-old, with all the distractability of that age.

No one disbelieves his basic story that something terrible happened. But the question of nuances becomes crucial when it turns out that Cummings did not initially get a full account of everything the boy said.

It requires some patience to follow Outcry through years of investigations that often yield one tiny micro-fact at a time. Even at the end, some of the story relies on innuendo and remains subject to a degree of speculation.  But Outcry takes a compelling, complex story and distills it into coherent drama that brings us a little closer to what feels like justice.