At a Little League game, the coach Chauncey Cunningham is encouraging his son Petey as he comes to bat. An old woman, Martha Murphy, comes by power-walking and chats briefly. Petey finally hits the ball over the fence. Kelsey sends a player to go get the ball and he discovers Martha, dead, her head crushed in by the baseball.
Later, Martha's daughter and son-in-law go to her home after the funeral and discover a box postmarked three days before she died. Inside is a voodoo doll representing Martha with a miniature baseball fastened to its head.
Stottlemeyer calls Monk in to investigate the case. He tries to explain but Monk is distracted by the fact that they've rearranged the squad room. Monk refuses to focus on the case until the officers set the squad room back the way it was. Natalie, who is interested in the voodoo angel, is informed that Reverend Hadley Jorgensen sold the voodoo doll but doesn't know who the buyer was. The postmark is legitimate and there seems no way it could have predicted Martha's date. Monk is more concerned about the placement of a wastepaper basket.
Monk goes to the crime scene and Kelsey testifies that Martha came by the same place every day when she was power-walking. Petey didn’t know Martha and no one on the team typically hit balls over the fence. When Stottlemeyer and Disher joke about the death, Natalie takes offense and insists that voodoo is really. Disher and Stottlemeyer try to suggest other theories but nothing seems to make sense.
The police discover another box with a voodoo doll. Ralph Ferris died several days ago, struck by lightning on a golf course. Ferris' landlord has discovered a voodoo doll, postmarked a week earlier. The doll has a lightning bolt fastened to its head.
Later, Monk is at home vacuuming and unplugs the phone to get behind the table. Natalie comes in and announces that she's taking him on a free vacation trip to a five-star hotel. It's a perfect vacation for Monk so he wonders what's going on. He says they have to call Stottlemeyer and Natalie calls the captain and makes sure it's okay with him. Monk points out that the phone is still disconnected. Natalie informs him that Stottlemeyer discovered a third voodoo doll.
Stottlemeyer and Disher go to the home of the third victim, Robert Boyd, and meet with his niece, Angeline Doerth. Outside, Monk arrives and Natalie refuses to come in. Meanwhile, Angeline explains that her uncle opened a package and fell over dead of a heart attack. She's an ER and tried to resuscitate him, but it was no good. Monk finally comes in and explains that Natalie is twisted up about the case and didn't give him the message. Stottlemeyer shows Monk the third doll, postmarked three days' earlier, marked to indicate the victim would have a heart attack. According to Angeline, Robert was obsessed with the voodoo killings and kept a lot of good luck charms. Monk goes over the house and notices that the victim had a horseshow nailed above a door. However, the horseshoe is nailed the wrong way down. Monk wonders why Robert didn't know how lucky horseshoes were supposed to work. Angeline talks with him and says that her uncle didn't know the first two victims. Natalie calls from the garage and says she wants to leave. Stottlemeyer suggests Monk try to act sympathetic.
Disher and Stottlemeyer go to Reverend Jorgensen's voodoo shop. The owner is doing a brisk business in selling voodoo dolls like the ones used in the killings. He admits that the doll that killer Robert is probably one of his but insists he has no idea how they're used and there was no way he could have caused the deaths.
Monk goes to see Natalie and discovers her cowering on the stairs. She finally explains that someone sent her a voodoo doll with its head cut off. Monk calls Stottlemeyer and then tries to get useful information from Natalie. The postmark is from Pacific Heights but Natalie doesn't know anyone there. The killer also misspelled her name "Teager" instead of "Teeger." Monk insists that it doesn't mean anything and assures her that nothing will happen to her. Natalie finally tells him that when she and Mitch lived in South Carolina. They lived next door to a voodoo priestess who once predicted that Mitch was in danger. Natalie didn't take it seriously and say anything, and Mitch was shot down the next day. She insists that voodoo is real.
That night Natalie tries to get to sleep but can't because of the ceiling fan. Disher stands guards while Monk and Stottlemeyer try to find a lead. He assures her that they'll have her in a safe house that afternoon but Natalie doesn't believe she'll be safe anywhere.
Monk and Stottlemeyer are working at the station. The mayor went public with the killings and the city has been flooded with voodoo doll mailings. Jorgensen has an iron-clad alibi for the three murders and Monk can't find any connection. When Monk warns that Natalie is losing it, Stottlemeyer has an idea. They call in Jorgensen to Natalie's house to perform a voodoo ritual to protect her. Jorgensen prepares a liquid and asks Monk to reattach the doll's head to the body. It takes Monk a long time to get it perfect. An impatient Natalie finally drinks the potion but Jorgensen warns that she was supposed to apply it to her neck, not drink it.
They call the ambulance and the paramedics arrive. One of them is Angeline. There's no room in the ambulance for Monk so Jorgensen offers to drive him in his van. As the voodoo priest insists that he didn't do anything wrong, Monk remembers that Angeline was in the newspaper photo of the dead man at the golf course. Jorgensen says that Angeline is a good person and has been at his store. Monk realizes Angeline is the killer. Here's what happened: she mailed empty boxes to herself to get the right postmark. She then waited until the right victims came up, people who lived by themselves and died under bizarre circumstances. She snuck into their houses after their deaths and planted the voodoo dolls. Then she killed her uncle inducing a heart attack with a drug, and planted the good-luck charms to make it appear he died because of fear due to his superstitions.
In the ambulance, Natalie notices that Angeline has spelled her name as "Teager" and realizes she's the killer. Angeline notices her noticing and prepares to give her an injection. Monk has Jorgensen speed up as they see Natalie struggling with Angeline. Jorgensen rams the ambulance, driving it off the road, and Angeline is stunned.
Later, Monk explains to Natalie that Angeline targeted her to distract Monk. He insists that he wasn’t distracted and is perfectly sane and rational... while touching parking meters.