Molly bribed Jim to come out of hiding and save Sherlock at the end of season 3, and paid for it by giving her body over to Jim for whatever he wanted. Jim took her up on the offer, but told her that he would collect at some other time, and proceeded to pull his little stunt with the TVs.

It worked and Sherlock was saved, but now Jim's back to collect, and Molly wants out of the deal.