Walls

S1, E7: After a college student is mysteriously killed just outside Dresden's office, Harry learns that she was coming to him for help when she died. The trail leads Harry to her boyfriend Dante, who has fallen in with a group of wealthy students with a dark secret they are desperate to protect. It turns out they are responsible for a series of brilliant thefts that have baffled the police. Somehow they are able to get past the most sophisticated security systems, take what they want, and depart without leaving a trace. But Dante and the others appear to be in declining health. Harry soon discovers that the boys are using magic to walk through walls, but the price of this power is that with each use, each boy's body is rotting from the inside out.