When you watch Elementary Season 4 Episode 4 online, Joan is approached by a former colleague at her old hospital to investigate the disappearance of Abby Campbell, a lab technician. Sherlock and Joan quickly discover that Abby has been murdered and her skeletal remains set up like a lab specimen in the hospital. Unfortunately, Abby was very well-liked and didn't seem to have any enemies, let alone someone who would want to kill her. And yet, Sherlock theorizes that she was likely strangled by someone who knew her. At the same time, Joan learns from a friend that an NYPD detective from the Coney Island Burglary division is investigating her for some reason, questioning her friends and not explaining the reasons for the questions. Joan must figure out why Detective Cortes is so fixated on her and what her motivation is for behaving in such a manner. Will Joan ever find out the reasons for Cortes's investigation? Will she and Sherlock be able to determine who killed Abby Campbell and why? And was it possible that she she had a secret side that her friends didn't know about? Find out the truth when you watch Elementary Season 4 Episode 4 online!