Sherlock must face his past when he travels to London to revisit an old case; Watson learns more about Sherlock's pre-New York life; Sherlock's brother, Mycroft, reveals some secrets.
The Jeffersonian team investigates the murder of Jamie Delcampo, a member of the Estrellas Locas gang, whose remains were found in a burnt out car. Meanwhile, having taken time off from the FBI in the wake of Pelant's latest assault on the team, Sweets ultimately decides to help with the investigation when he discovers that a young boy from the center where he volunteers is the son of one of the gang members.
When Kate asks Pete for more responsibility, he entrusts her to put Bert to bed and help him coach Bert's soccer team. Before soccer practice, Bert drinks Kate's coffee and becomes a wild man on the field before crashing. Meanwhile, Warren and Hillary spill salsa on Diane's immaculate white couch and try to hide it from her.
After returning from Haiti, Casey has an identity crisis and thinks being a disc jockey might be his new calling. When Mindy and the office go to a music festival for their "work retreat" to see Casey perform, the substance-filled surroundings lead to a series of disasters. Meanwhile, back in New York, Jeremy hires a new doctor, whom Mindy doesn't particularly like after he saves the day during an emergency delivery.
Thinking Schmidt has chosen to be with Cece, Jess and Nick invite him to go on a double date with them. Nick is caught between loyalty to his friend and loyalty to his girlfriend when he finds out a shocking secret. Meanwhile, Winston promises to get the foursome a table at an ultra-exclusive restaurant that doesn't take reservations.