Arthur is a happily married young businessman until news strikes about his investor embezzling his entire fortune. Panicked, Arthur calls his wife's godfather, Spencer, for advice. Spencer realizes Arthur is not only nervous about the money, he's also afraid of upsetting his beautiful and sheltered wife, Lucinda. Spencer advises Arthur to swallow his pride and ask Lucinda's stepmother for money. Arthur is resistant; nevertheless, seeing his jubilant wife later trying on different gowns for their upcoming charity ball, Arthur determines to do whatever it takes to keep his wife happy.
The stepmother, Mavis, declines Arthur's request. She makes a point of highlighting that Arthur trusted the wrong people with his money and that's his problem. Spencer interjects the money Mavis has came from Lucinda's father and she should be entitled to it. Mavis disagrees and sends them off. That night, an odd noise wakes up Mavis. Looking under her bed, she sees a Murcielago, a bat-like Wesen. Mavis tries to flee the creature, yet she is caught on the second-story landing. The Murcielago releases an ear-splitting screech, which breaks the glass surrounding them and causes Mavis' ears and eyes to bleed before she falls to her death on the floor below.
Nick wakes up from having nightmare about his parents' car accident almost 20 years ago. Nick admits to Juliette for the first few years he actually wished he'd died with them. It was only through the strength of his Aunt Marie that he was able to survive. Juliette mentions how looking for more information concerning their accident may help bring some closure for Nick. The following morning, Juliette contacts the police detective who handled Nick's parents death, Arnold Gubser. Gubser agrees to call Nick directly and let him know the details of their case.
Nick and Hank investigate the crime scene at Mavis' estate. They're confused by all the broken glass and the absence of any cuts on the victim's feet. Did the murderer break the glass after Mavis was killed? The detectives interview Mavis' two daughters who implicate Arthur and Spencer, knowing they'd asked their mother for money just the other day. When Nick asks Arthur, Spencer and Lucinda to come downtown for questioning, Nick notices Spencer is a Murcielago.
During questioning, Arthur tells of first dancing with her two plain stepsisters at a ball before meeting Lucinda. Nick immediately begins seeing this case as a bizarre Cinderella tale with the wicked stepmother and everything. Mavis went so far as to keep Lucinda out of the will for her father's inheritance completely, leaving it to her own daughters. Spencer speaks of Henry entrusting him to look after Lucinda once he passed on. Henry was a bad judge of women. Always trusting them to do the right thing, they never did.
Det. Gubser phones Nick to share the file on his parents' accident. A year after the crash, the case was labeled a homicide. Nick couldn't be more intrigued. Gubser includes a list of the four suspects they could never pin enough evidence against. Three of them happened to be recently deceased Wesens Nick encountered during the Coins of Zakynthos caper. The fourth is a man named Akira Kimura. Nick wonders what this all means and how he can find Kimura.
Lucinda is determined to go over to Mavis' house and pay respects to her stepsisters. Arthur protests, trying to keep Lucinda in the sheltered world he's made for her, yet this time timid Lucinda stands up for herself. At Mavis' house, stepsister Tiffany isn't glad to see Lucinda. Tiffany tries to blow Lucinda off as she gets into her own car, ignoring Lucinda's condolences. Lucinda claims to only have one more thing to say as she morphs into a Murcielago and lets out a shriek so powerful, the car windows are shattered and Tiffany's head hemorrhages.
In Aunt Marie's trailer, Monroe finds a picture of the Wesen Nick saw Spencer become and tells him he's a Murcielago, aka "bat out of hell." With their ability to generate high-pitched sounds capable of breaking glass or rupturing blood vessels, their sound can kill anything. Nick finds an old weapon in Aunt Marie's trailer that creates a similar-type noise, although it specifically incapacitates the Murcielago and their ultra-sonic sound waves. During the test run of the weapon, the device breaks a glass in front of it and the boys think they've found their gun.
Now prepared to face Spencer, Nick goes to Mavis' estate thinking he may try to kill Tiffany next. There Nick finds Spencer standing next to the obliterated car with Tiffany's dead body inside. Spencer tries to explain he didn't do it as Nick arrests him and reveals he's aware Spencer is a Murcielago. However, without a weapon, Nick doesn't know how he can get the charges to stick. The problem is solved when Spencer tells Nick and Hank he will confess to the crimes.
During Spencer's confession, he alludes to his special Wesen powers, which cause Hank to think Spencer is some sort of loon. After Hank leaves the room, Spencer reiterates his innocence yet takes responsibility for not doing a better job of taking care of Lucinda. Once she's threatened, she has no conscience. Spencer calls Nick to action. The other stepsister, Taylor, doesn't have long to live. If she dies, all the money will go to Lucinda, and Nick will never be able to prove her guilt. As Hank and Nick head off to Taylor's, Spencer escapes the interrogation room by screeching and leaving through the broken window.
Nick calls Taylor to warn her, but it's too late. Lucinda is already in the house. Lucinda tells Taylor she is now going to look just like her mother and sister: one big, happy, dead family. As the detectives arrive, they can hear Taylor's screams for help from inside the house. Bursting through the doors, Lucinda escapes to another part of the house. Monroe arrives with the sonic weapon. Monroe and Nick use it to force her out. Lucinda covers her ears and leaps from the second story window to the backyard. Spencer finds her there, and Lucinda begs him for help. Spencer tells her he should've helped her years ago.
Nick hears the Murcielago shriek and runs toward the backyard. Spencer is kneeling over Lucinda's dead body with blood tricking from her eyes and ears. The nightmare appears over until, with a dying breath, Lucinda reaches up and bites Spencer in the neck, killing him as well. Monroe stands over the bodies with Nick and wonders how Nick'll explain this one in a rational non-Wesen way to the police. Using his head, Nick turns in Aunt Marie's siren as the murder weapon to explain how mortals could have committed these crimes.
Back at his house, Nick is looking over the evidence Det. Gubser sent concerning his parents' murder. Juliette is sorry what was supposed to bring closure has only brought more questions. Nick reassures her. It's something he needed to know... and something he's going to have to deal with. Nick stares long and hard at the photo of Akira Kimura.