In Plain Sight Episode 3.08 Son of Mann

Marshall's newest witness, Billy, was once a drug runner who witnessed a drug-deal gone deadly. Now taken under Marshall's wing, Billy is admitted into Albuquerque's best boarding school and urged to find friends who will accent his personality.

If this wasn't enough of a load, Marshall's father, Seth, shows up in Albuquerque on a sting operation called Operation Falcon that targets open warrants in the area. Marshall's straight-laced style contrasts with his father's maverick approach when he and Mary join Seth on his assignment.

All hell breaks loose, when Marshall find out Billy is involved in a one of Seth's open-warrant apprehensions of a local criminal named Liam. Marshall seemingly works against his father in clearing Billy of any wrongdoing after finding out his witness' ulterior motive and relation to the crime.

Meanwhile, Brandi shows up back in Albuquerque. Peter openly accepts her return and she promises him that she'll pay him back the $20,000 she borrowed from him. Not only does she return the money, but she's got a giant surprise for Mary as well.