In the third episode of Dead Boy Detectives, the detectives encountered a series of mundane ghostly issues until an elderly woman revealed a harrowing tale. She spoke of her home, where her sister's husband had slaughtered his entire family in a fit of rage, sparked by a rumor that his wife might have been unfaithful. She confided that before her demise, she could sense a "presence within" and desired to ensure her family's eternal peace before she could move on to the next realm. As a token of gratitude, she offered a jar filled with coins.
The trio embarked on the perplexing Devlin murder case. Niko and Edwin received pertinent documents from the librarian, Maxine, while Crystal and Charles sought the counsel of Jenny, the butcher shop owner and their landlord, delving deeper into the mystery.
After leaving the library, Niko and Edwin crossed paths with Monty, who regaled them with tales of his ghostly visions following a near-death experience. His keen interest in astrology and particular fascination with Edwin were evident, much to Edwin's discomfort.
Meanwhile, Night Nurse's request to descend to Earth was denied due to a lack of specificity in her paperwork. Elsewhere, Edwin, Charles, and Crystal arrived at the haunted Devlin residence, witnessing a macabre replay of the father repeatedly murdering his wife and daughters for three decades. Edwin explained the Stone Tape Theory, revealing that such a repeating cycle stemmed from the profound trauma associated with the grisly event. The ghosts were trapped, and the only way to liberate them was to locate and destroy the triggering artifact.
They surmised that the trigger was a letter the man received from someone named Hudson, which incited him to commit the heinous crime. They destroyed the letter, yet nothing changed. It was later revealed that it wasn't his wife's infidelity but rather one of their daughters' intention to attend Hudson University that had provoked his rage. Through the daughter's diary, they discovered how her father's controlling nature had escalated, and her desperate desire to escape.
Charles, himself a victim of abuse, grew increasingly agitated and attempted to strike the man, only to become trapped in the relentless cycle. Crystal and Edwin brainstormed and realized that the music was the true trigger. They searched for its source and discovered a concealed cabinet. Shockingly, it transpired that the father had installed cameras throughout the house, monitoring his family's every move.
Edwin and Crystal attempted to erase the song from the tape, but their efforts were interrupted by the arrival of a misery wraith, a creature from hell that fed on negative emotions. Edwin advised Crystal to focus on "positive thoughts," but her toxic ex-lover, David the demon, invaded her mind, rendering her incapable of positive thinking. Amidst this chaotic scene, Edwin somehow managed to erase the files on the tape, breaking the cycle, and they fled the cabinet.
The trio scurried away from the house, narrowly escaping the clutches of Death as he arrived to reclaim the lost souls. The case was finally solved.
Meanwhile, roused by the sprites, Niko arrived with pots and pans, intent on assisting her friends, though she arrived a bit too late. Nevertheless, her efforts were acknowledged. As they made their way back, they encountered Monty again, who seemed only interested in conversing with Edwin.
Elsewhere, in the Afterlife's Lost and Found department, Night Nurse managed to gain insights into Edwin and Charles through the Devlin murder case's victims - the daughters, who spoke of their saviors.
