What is the episode of law in order with the teenage boy chained to the radiator?

The episode you're referring to is titled "Runaway," which is the 21st episode of Season 10 of Law & Order: Special Victims Unit. In this episode, a teenage boy is found chained to a radiator in a basement, leading the SVU team to investigate a case of child abuse and trafficking. The storyline explores themes of neglect and the complex dynamics of family and survival. The episode highlights the challenges faced by victims and the efforts of law enforcement to bring justice.