The episode begins with two security guards watching surveillance footage where they see a woman being attacked by someone wearing a hood. The guy tells the girl to call 911 and rushes into the back alley. He does not find any body. He checks the dumpster and he finds the woman’s dead body inside. Next, Castle has broken his leg. Ryan and Esposito arrive to pick up Kate. Castle is upset that they aren’t taking him for the new case. He is totally bored. Ryan checks out the binoculars that Alexis gifted her father. The trio leaves.
They arrive at the crime scene. Lanie tells Kate that the victim’s name is Clara DeWinter and she was struck repeatedly with a bat that they found in the alley. She also says that Clara was an IRS agent and she worked in the nearby building. They go into the building and talk to Selena, the girl who first noticed the attacked on the surveillance monitor. Esposito tells Kate that the killer is wearing an IR light on his head. This light is invisible to the naked eye but it blinds the camera. Kate infers that the murder was premeditated. They catch a glimpse of the killer’s car and Kate tells them to tell the tech team to try enhancing the image.
Later, Kate talks to Clara’s husband, Gavin. Gavin tells Kate that Clara investigated tax evaders. Gavin tells Kate that Clara had a lot of enemies and one of the guys she was investigating threatened her when they were at a restaurant having dinner. Ryan and Esposito question Charlie Blunt from the IRS about Clara filing a report against the guy who threatened her. Blunt tells them that there was no report filed. He says that the agents don’t report any official threats because it is a headache for the senior management and it affects their performance report. They tell Blunt that they will have to take a look at all the tax evasion cases that were filed recently. There are a lot of them and Kate tells the duo to make a list of all the tax evaders and get Gavin to identify the guy who threatened Clara.
At home, Castle is bored to death and decides to use the binoculars to check out whatever is going on in the building across his window. He witnesses a murder. He calls Kate. Next, Ryan and Esposito are in the house and Castle sees that they are shaking hands with the so called murderer. They tell Castle that there was no blood and no body. Castle tells them that the girl was having an affair with someone and her boyfriend found out. They had a fight and the man went after her into the bedroom with a knife. The blinds were pulled and hence he couldn’t see what happened in the bedroom. Esposito tells Castle that there was no murder because he spoke to the girl over the phone.
Castle tells Kate that he is sure of what he saw. Kate explains that he was bored, was on pain meds and saw what he wanted to see. A “Rear Window” scenario. Castle is not convinced and continues to keep a watch on that house. In the morning, he tells Kate that the man looked tensed and he slept on the couch. Why would a man sleep on the couch when he has a perfectly nice bed? Castle is sure that he hid the body in the bed and Ryan and Esposito did not check the bed. Kate doesn’t want to hear more and leaves for work.
At the precinct, Ryan tells Kate that they found out a guy who tried to muscle through security to get through to Clara. His name is Dan. He says that Dan had to face criminal charges due to Clara’s audit and his wife filed for divorce. Castle is still keeping a watch on the guy and Castle sees that the man has some ropes and a tarp. Castle also sees that he is trying to wash blood off his hands. At the precinct, Dan is brought in for interrogation. Dan tells them that Clara wanted him to help her disappear and in return she would make the criminal charges go away. He tells them that Clara wanted a new identity.
Castle calls Kate and asks her to come home. Kate does not believe a word that he says. She thinks that he is bored and misses her and therefore is making up stories so that she would be with him. Castle is shocked that Kate doesn’t believe him. At the precinct, Esposito tells her that Dan’s alibi checked out. Kate tells him to dig deeper into Clara’s life. It is 3 am and Castle sees the man trying to pull a huge rug across the floor. He knows that he is moving the body and tries to record it, but he misses it. In the morning he discusses this with Alexis and both of them watch the house. They see him wear a gas mask and gloves. At the precinct, Ryan and Esposito tell Kate that Clara was hiding a lot of money and all the deposits came from the crime boss, Tommy Valentino.
At home, Castle and Alexis see that the man walks out of the bedroom with bags and he has the girl’s purse. He is also shredding her identity. Castle decides to break into the house and collect whatever is there in the shredder. He asks Alexis to keep a watch and make sure that the man doesn’t return. At the precinct, Tommy Valentino tells Kate that Clara was his tax consultant and he did not kill her. He says that Clara wanted to get away from her husband because she was scared of him. Valentino’s alibi checks out, and they deeper into Gavin. They find out that Gavin recently took out a life insurance policy on Clara. On the other hand, Castle manages to get inside the house, but he falls down.
The man arrives but he does not see Castle because Castle is on the floor. Castle overhears him talking on the phone and he learns that his killer is going over to Jimmy’s boat. The man goes into the bathroom and Castle manages to collect the evidence and gets out of there. They tell Kate what they did. Castle shows her the invoice from a storage facility and he thinks that he is hiding the body there till he moves it on to Jimmy’s boat. Later, they see that the boyfriend arrives to meet the girl and the man pushes him out of the house. Castle wants Kate to talk to the boyfriend. She goes to talk to him. She comes back and tells Castle that the guy and Emily met at some classes. She says that the boyfriend has been texting her for several days and he did not receive any reply.
Castle tells Kate that they should check the storage unit. They go to the unit and find the rug, but there is no body. Kate checks the bags and finds wigs, clothes etc. The security guard arrives with a gun drawn at them. Next, Gates is pissed over the “illegal search” they conducted. She warns Castle to stay away from that man. Ryan tells Kate that Gavin was acting really strange on the night of the murder but they have no proof. At home, Kate is all dressed up to leave for dinner and Castle notices that the man takes out a soda from the cabinet instead of the fridge. Castle is sure that Emily is in the refrigerator.
Kate has had enough and decides to put an end to this. She goes to the apartment and the man lets her in. He appears friendly but when Kate goes near the fridge, he freaks out and grabs her. He pulls out a knife and just then the lights go out. Castle immediately calls the team and they go to the apartment. Ryan and Esposito break open the door and SURPRISE. Kate, Martha, Alexis, the boyfriend, the killer, Emily and few others are present in the house. Kate had staged all this to give him a birthday surprise and Castle admits that this was the best birthday gift by far. At that moment, a thought strikes Kate and she tells Castle that she just solved her real case.
The next day, Kate brings in Selena who first witnessed the attack. Kate figures out that the footage was faked. She also knows that Selena and Gavin knew each other for a while because they worked at the same place a year ago. Selena tells her that she did not kill Clara. Kate wants her to tell her who killed Clara. Later, we see that Gavin is arrested and brought in. Kate tells Ryan and Esposito that Gavin and Selena were having an affair and Gavin decided to get rid of Clara. Instead of a messy divorce, they decided to go for the killing.
Gavin bludgeoned Clara after dinner and put her in the dumpster. They staged the attack and Selena fed in the fake footage. Case Closed. At home, Castle thanks Kate for the epic surprise and he assures her that he will top it when it’s her birthday. The episode ends.