How did David convince Maddie to keep the agency open?
In the pilot episode, after a man died of a stab wound at Maddies feet, the criminals met up with the two at her house where they threatened their lives. Thus, the two were thrown into the case when David convinced Maddie it was safer to search for the stolen diamonds rather than turning the main clue to the police. Along the way, he leaked to the press that Maddie and he were going into business together. Once they diamonds were recovered and the criminal was caught, David kept offering the prospect of going into business together, which the episode concluded with Maddie saying, maybe.