The episode begins with Watson and Holmes attending an AA meeting. Watson looks at Holmes and he seems to be slightly lost. She touches his shoulders and he gets up yelling. He then shakes himself and leaves. Outside, he tells Watson that he hypnotized himself to avoid listening to the sob stories. Watson asks him as to why doesn’t he listen if he doesn’t want to share. He explains the Attic theory in which the brain stores only what is useful. So he blocks out the useless stuff. Watson then tells him that she will be going for dinner tonight and will be gone for two hours. Holmes receives a call from Gregson. Next, they arrive at the crime scene. A dead body is lying in the hallway.
The man is shot in his face and his wallet and watch are missing and the drawers are tossed as well. Looks like he walked in on his burglar! Bell and Gregson classify this as a robbery-homicide case. The neighbor was the first one to see the dead body and call 911. Watson examines the scene and tells Bell that this is a robbery and a homicide case; by two different perpetrators. He then says that the woman who shot the victim was seated on the leather chair. He knows it is a she as he can smell lady’s deodorant on the leather. The robbery was committed by a strong man as he says that a large armoire is missing. This he judges by the pattern on the wall. Watson arrives with a picture of the victim and points out that there was an armoire at the same spot.
He follows the drag marks and kicks open the neighbor’s door; and the armoire is in his apartment. So we have the thief! And now we need, is the killer!! They interrogate the neighbor. He tells Bell that Casey, the victim, was already shot when he saw him. He did take his belongings and armoire but he never laid a finger on him. Holmes, who is watching the interrogation, is annoyed as he had clearly mentioned that there were two perpetrators. Bell comes out and tells them that the neighbor says that he saw a woman on the stairs; Bell thinks he is fabricating the story after he heard Holmes’ theory. But Holmes thinks they should get a sketch made. Gregson calls for an artist. Later, Holmes tells Watson that she is dining with her ex.
He says that she should sleep with him as she hasn’t had sex for a while and she lacks an orgasmic gait. He says that sleeping with him would do wonders for her mood. Next, Watson meets her ex Ty, who says that he and her parents are worried about her. The following morning, Holmes can tell that she didn’t sleep with her ex. He is going through Casey’s autopsy and notices a rare genetic disorder of the cornea. She tries asking him about London; but he refuses to speak. Just then Bell calls; they found the woman from the sketch. Bell then asks him to come to the hospital. He then takes Watson and Holmes to a room where we see a woman lying on the bed. She is the same woman from the sketch and her name is Yvette Ellison.
But she has been in a coma for the past three days as she tried killing herself with pills and vodka. so, it appears that the neighbor lied. Holmes can smell the same deodorant. He feels that she is faking it. But Watson checks her vitals and finds it consistent with a coma patient. Looks like a dead end! But Holmes says that Bell found the right face but the wrong girl. Holmes tells her about the book he found at the bed side table which says: To Yvette and Rebecca on your 5th birthday. This means that Yvette has a twin sister. Later, Holmes finds out that Yvette and Rebecca are the twins of the recently deceased Charles Ellison; the shipping millionaire. They go to meet Rebecca.
But they are shocked to see that Rebecca is nothing like Yvette. Rebecca tells them that they are fraternal twins, not identical. At home, Watson finds a violin and asks Holmes to play it to relieve stress. He tells her that he doesn’t play anymore. Ty calls and when Watson goes to take the call, Holmes sets fire to the violin. Watson extinguishes the fire. Just then Gregson calls; there is another murder and with the same gun that killed Casey. So clearly the neighbor isn’t their guy. Holmes points out that this woman, Anna Webster, suffered from the same genetic disorder of the cornea. This means that Casey and Anna were brother and sister. They were half siblings. But they didn’t know about each other’s existence.
So, both shared a mystery dad and they were murdered with the same gun; obviously this is no coincidence. Bell arrives stating that Anna filed a complaint few weeks ago as she thought that a guy was following her. He also shows them the picture that Anna shot from her window. Gregson knows this guy. They go to meet Mike. Mike tells them that he can’t say anything as per the client privilege. Holmes takes him aside and tells him that he knows that Mike has turned to meth to stay awake for long hours and can also tell that the stash is nearby. He says that he would tell Gregson and Bell anything if he gives them the information. Mike places a file on the desk and leaves. Next, they go to meet Rebecca and ask her why she had Mike follow Casey and Anna.
They know that they were her half siblings and this, their father told his daughters on his deathbed. Charles left his fortune to Anna and Yvette but they could sue them for their share and that is why the sisters had them followed and then killed them. Anna denies killing them. Anna tells them that she and her sister wondered about what to do as they didn’t want to give away millions to some strangers and that is why they had them investigated. But then Yvette started seeing a married man and also started drinking a lot. She then tried to kill herself. Holmes questions the suicide attempt and feels that Anna compelled her sister into committing suicide. Anna slaps Holmes. He then asks her why she disguised herself as Yvette and also wore her perfume. She thinks Holmes is insane.
Later, the cops let her go as the security cameras prove that she was home, while the murders were being committed. Next, Watson and Holmes are at the AA meeting. He still feels Rebecca tricked them. They then listen to an addict’s story where she tells them as to how she had an affair with a married doctor and how he went to jail for supplying her with drugs. A thought strikes Holmes and he says that they need to leave. Holmes walks into the room where Rebecca is reading to Yvette. He calls her a murderer and tells her that she tampered with the security cameras. He then tells her about the third heir, Mary Margret and tells her the address. Rebecca appears shocked. He tells Anna that he will be watching over Mary.
Bell arrives and tries to take Holmes away but Holmes pushes him. He then arrests Holmes for assault. We then see that someone is breaking into the house that Holmes was telling Anna about. As the murderer tries to move to kill the woman, the police catch her. It is Yvette. Rebecca is totally confused. Watson tells her that Yvette was in a medically induced coma. She had an affair with a married doctor who put her in and out of a coma when she needed. That is how she managed to kill Casey and Anna. But she was too weak and so she had to be seated while she shot them. Holmes tells her that the third heir was just a trap. He created the commotion to lure the doctor in. She knew that he would tell Yvette.
Despite hearing all this, Rebecca thinks of getting an attorney who can help Yvette. Holmes then asks her to think as to why Yvette stayed in coma after the two murders. That is because she was then planning to kill Rebecca. Case closed. At home, Watson talks to Holmes about listening in the meeting. She thinks she is doing some kind of penance for what happened in London, nut not knowing it. He tells her that one always knows it; else without that it wouldn’t be penance. Later, Holmes opens a violin box. In her bedroom, Watson hears him playing. The episode ends.