Director Rudy Valdez on his HBO documentary ‘The Sentence’

The new documentary ‘The Sentence’ opens with a Michigan family hustling to get six-year-old Autumn ready for her dance recital as her two younger sisters play in the background. Then the phone rings. It’s an incoming call from a federal prison, where their mom is being held.

Filming this scene is Autumn’s uncle, Rudy Valdez. His sister Cindy, devoted mom of three very young girls, was just beginning a mandatory 15-year prison sentence on conspiracy charges related to drug crimes committed by her then-deceased ex-boyfriend years before. In the intervening years, Cindy had completely changed her life, but the law was indifferent.

In ‘The Sentence,’ Valdez follows his family through the years-long nightmare of his sister’s sudden incarceration.

Cindy’s husband Adam, as well as her parents, work to raise Cindy’s three daughters with as much connection to their mom as possible, through phone calls and occasional road trips from their home in Michigan to a prison in Illinois where Cindy is first incarcerated.

As time goes by, the strain of the separation deepens, especially when Cindy is moved to a much more distant prison in Florida.

For more than nine years, Valdez kept his camera rolling as his nieces grew up and he and his family desperately tried to find a way to shorten Cindy’s prison term.

‘The Sentence’ premiered at Sundance this year, where it brought theater-goers to tears and won the Audience Award for Documentary.

But when Valdez first starting filming, awards and festivals were the furthest thing from his mind. He tells us about the moment he realized he became a filmmaker and that this project would be a documentary.

‘The Sentence’ opens in theaters on October 12, and will premiere on HBO on Monday, October 15.