"Who Ya Gonna Call?" is an episode of the dramedy Psych which makes suitable viewing for Halloween. It originally aired in the US in 2006, during Season 1. The episode's title is a reference to the 1984 movie, Ghostbusters.
Created by Steve Franks and broadcast on the USA Network, Psych is an American detective comedy-drama (also known as a "dramedy") which follows Shawn Spencer (played by Jame Roday), a young crime consultant who pretends to have psychic powers, when instead he is simply using a heightened sense of observational skills and detective instincts above the rest of the Santa Barbara Police Department. He chose to pretend to be a psychic after numerous tips he called in to the police department made them suspicious as to his overt knowledge of the crimes. Shawn is followed around by his best friend and reluctant partner, Burton "Gus" Guster (played by Dulé Hill), as well as his father, Henry Spencer (played by Corbin Bernsen) who is a retired member of the police force, who also taught Spencer to be a super sleuth.
The episode begins, with "psychic" detective Shawn Spencer and his partner Burton "Gus" Guster hearing about a doctor, Dr. Blinn, who had been murdered in his office. Shawn and Gus arrive at the crime scene. Head detective Carlton Lassiter quickly removes them from the scene, but not before Shawn gets a look at the body, notices he had a trauma to his head, sees the weapon and a chewed toothpick next to him.
Shawn and Gus go to the psych office, where a man named Robert Dunn walks in and asks them for help. He tells them a ghost has been haunting him in his house for some time and is trying to kill him. He shows them strangulation marks on his neck to prove it to them. Shawn believes this man to be crazy but Gus believes him and convinces Shawn to take the case.
The three go to Robert's house. Robert tells them that the ghost is leaving a perfume scent around, and rearranging his furniture. Shawn notices that the place is a mess and some pictures with Robert's face crossed out.
Robert begs Shawn and Gus to stay the night, which they eventually agree to do. Gus asks Shawn how they are going to get rid of the ghost. Shawn tells Gus that he has already solved the case but there is no ghost. Robert has an ex-girlfriend, who is angry at him, is trying to scare him and drive him crazy. From the pictures, he figures out who Robert's ex-girlfriend is and decides that he and Gus will contact her the next day. The two then go to sleep. However, they are woken up in the middle of the night when a fire breaks out in Robert's house, which Robert is convinced is the work of the ghost.
Meanwhile, Lassiter, and Juliet O'Hara discover that Dr. Blinn was having a session with someone named Regina Kane when he was murdered. They suspect that she was the murderer. Unfortunately, they are not able to find her. Shawn passes them and remembers the name Regina Kane.
Shawn and Gus go out to meet Robert's ex-girlfriend in San Francisco. She tells them that she broke up with Robert because he was cheating on her. She says that he would disappear for stretches of time, without being able to be contacted, and she once saw him with another girl but when she confronted him, he claimed that his name was Martin Brody. Shawn accuses her of being angry at Robert for cheating on her, and out of anger, causing him to believe there was a ghost in his house and even going as far as trying to kill him with a fire. She tells Shawn that although she was angry at first, she is now over it and has not thought about him in months. Shawn notices an engagement ring on her finger and realizes she is telling the truth.
On their drive back, Shawn and Gus are nearly rammed into by another car. The driver crashes into a pole, then quickly flees, but not before Shawn notices a chewed toothpick, similar to the one in Dr. Blinn's office, in the car. They realize this person also killed Dr. Blinn.
The two go back to Robert's house, but see that he is not around. They search for him, and find a secret room hidden in the house. They enter it, and see it is filled with women's things, including dresses and wigs. Shawn figures out that Robert suffers from multiple personality syndrome, and has been haunting himself (explaining the perfume scent, and the rearranged furniture.)
They eventually find Robert and are able to trigger his other personality, a girl named Regina Kane, who Shawn remembers that the police are looking for. They talk to Regina and realize that she is not violent and is not the one who killed Blinn or started the fire. They realize there is a third personality, the Martin Brody, who his ex-girlfriend says he once claimed to be. Regina tells Shawn and Gus that she is going to see another doctor shortly and leaves.
Shawn and Gus tell Lassiter and Juliet that they have found Regina. They see Regina's patient file and it is revealed that she went to see Dr. Blinn to get gender reassignment surgery. The Martin Brody personality knew about this and knew that if she had this, he would be getting the reassignment too. Therefore, he killed Dr. Blinn and now plans on killing Regina's new doctor as well. Shawn, Gus, Juliet, and Lassiter rush to the doctor's office, and rescue the doctor just before Martin Brody could kill her.
At the end, it is revealed that Robert has been put into a mental hospital.