Elementary "Corpse De Ballet" (S02E15): A note on Holmes' door boldly states "coitus in progress," as Watson continues about her daily routine. Watson points out Holmes' promiscuity and he feels a bit judged. In the meantime, a dancer is found dead at a ballet rehearsal.
The duo show up to find that someone rigged the backdrop to cut the dancers' body in half and dump her onto the stage when it came down. Detective Bell is surprisingly off desk duty and helps track down the place when the dancer was killed with a knife. The murder weapon turns out to be a boxer cutter owned by the lead ballerina, whom they interview (Holmes is a fan). Watson calls out Holmes on his fanboy-ness towards her, but she is called away when a homeless man she knows was taken to a hospital and apparently had a psychotic episode.
Bell and Holmes visit the deceased dancer's ex-boyfriend, whose alibi doesn't check out. The prima ballerina and her lawyer show up at the precinct, but was uncooperative and going to leave the country to teach a class, so Gregson charges her with the murder.
Watson awakens the next morning to find the murder suspect coming out of Holmes' room. Apparently, she initiated the encounter but Holmes followed through only to verify his suspicion about her have a torn rotator cuff. Watson heads off to track the homeless man's missing friend and Holmes heads to meet with the diva's lawyer to start going through her files.
Watson finds the missing man's sister, who informs her he has extreme PTSD and drug issues. Pulled away by a text from Holmes, Watson joins him to see the paparazzo the diva put a restraining order on and sued her for destroying his camera. He was not very cooperative either, and the duo are called back by Bell, who has discovered from a stolen voicemail that the diva was dating the dead girl. They interview her and she confesses to seducing the girl and guilting her into giving up the lead role. Holmes concludes her phone must be cloned and the paparazzo confesses to it, but also has an alibi.
Holmes probes further and determines the stolen voicemail was recorded from the actual phone and is a recording of a recording. Holmes questions Watson on why she is helping this homeless man and she reveals that her biological father is schizophrenic and homeless. She volunteers at the homeless shelter to see him, unable to convince him to stay on his medication, though she hasn't seen him in nearly two years. Going through the missing man's bag, Watson discovers the sister she met wasn't really his sister...
Holmes discovers a noise on the voicemail matching one from the automatic door closer in the diva's lawyer's office, so he meets with the lawyer and accuses him of murdering the ballet dancer, who turns out to be his ex. He kicks Holmes out, claims he has no evidence, and is hiding the diva from Holmes so he can't reveal the truth.
Holmes has a House, M.D. moment and realized the lawyer must have a key piece of evidence to release during the trial. Gambling on that, the police search his office and find the stolen hard drive from the theater the night the murder occurred. Holmes, Gregson, and Bell arrest the lawyer in the courthouse bathroom.
Now symptahetic towards Watson's views of homeless people, Holmes suggests they hand out blankets to individuals living in the park.