A surprise visit from Sherlock's brother Mycroft leads to discord between Holmes and Watson. Meanwhile, Sherlock and Joan investigate a missing person's case that takes them into the world of unmanned aeronautics.
In order to protect the fortune of a Manhattan family and to reveal an imposter, Neal goes undercover as a butler.
A hacker claims to have pertinent information about the leak at Princefield; Patty's former colleague offers her services to Ellen.
A high-profile reporter, who happens to be a close friend of Frank's, is in town and almost assaulted. Jamie's undercover case reaches a critical stage.