When the Summer Olympics added women’s boxing in 2012, 17-year-old Claressa “T-Rex” Shields set out to become the first gold medalist. Not just for herself, but for her family. Her dad is an ex-con, her mom is a drinker, and her 14-year-old sister Brianna describes their Flint, Michigan, hometown as a hellhole. Codirectors Drea Cooper and Zackary Canepari follow Shields for several months before and after the London Games. Her coach, Jason Crutchfield, admits that he had no interest in women boxers when they first met, but her talent and Muhammad Ali–size ego won him over.

Now he’s like a surrogate parent, but Shields is on her own in China, where she competes in the world championships. Other challenges include bickering relatives and a forbidden romance. After the Olympic Games, she meets with Olympics reps who advise her to act more like gymnast Gabby Douglas, or her strong personality (“I like to beat people up”) will hinder her ability to secure endorsement deals. She becomes a champion by being true to herself, but she can capitalize on her success only by becoming someone else.

There have been more inspiring boxing documentaries, like Nanette Burstein and Brett Morgen’s On the Ropes, but rarely has one shown how little fame is worth if you have to sell your soul in the process.