The 16-year-old boy who was allegedly tortured, beaten and chained to a fireplace in a Tracy home escaped his captors when he found a key that unlocked his shackles, according to court documents released today.

The boy had been imprisoned for more than a year until Dec. 1, when he found the key while being driven by his alleged tormentors in an SUV, Tracy police Detective Ryan Knight wrote in an affidavit filed in San Joaquin County Superior Court.

When they got home, the boy freed himself with the key, leaped over an 8-foot-wall from the backyard of the home on Tennis Lane in central Tracy and limped into the In-Shape Sport fitness club. He had cuts and sores and was covered in soot, employees said. A 3-foot chain was attached to his right ankle.

Read the whole story and see the video here.