Series 2

Jenny was the teenage girl who had been forced into porn. Baba was the person behind the porn ring. When Luther rescued Jenny, Baba told him "You've stolen my property." So the deal was that she was holding the safety of Jenny and her mother over his head. He had to get the information she wanted, or she would have them done away with.

firstly, he had to get the russian to drop charges on the crazy nephew to save jenny

but they recorded him agreeing to help them, which they used as leverage to get him to do more chores.