T23, E1: Part 1 of 2. As the investigation into a sex-for-housing scheme expands, Benson's loyalty to Garland is tested. Rollins and Carisi try to keep their witnesses on board when a powerful congressman is identified as a suspect. The search for a missing witness leads Fin and Kat down a dangerous path. Guest starring Ben Rappaport, Terry Serpico, Octavio Pisano, Glenn Fleshler and Isabelle Poloner.