A horror mystery story could revolve around a haunted mansion. A family moves in, not believing the rumors of it being haunted. Strange things start to happen - objects move on their own, they hear unexplained whispers. As they dig deeper, they find out that the previous owner was a deranged serial killer who hid his victims' bodies in the walls of the house, and their spirits are now trapped and angry.
A small town is haunted by a series of disappearances. Every full moon, someone vanishes without a trace. The main character, a detective, starts to investigate. He notices that all the victims had visited an old, dilapidated mansion on the outskirts of town before they disappeared. When he goes to the mansion, he finds it filled with strange symbols and a locked room. As he tries to break into the room, he hears a deep growling noise. The mystery could revolve around a cult that used to operate in the mansion and is now kidnapping people for a dark ritual.
You could use 'The Shadow in the Alley'. It gives a spooky and mysterious feeling. Just the thought of a shadow in an alley makes the reader wonder what's lurking there. Is it a person? A supernatural being? It sets the mood for a mystery.
One idea could be a missing heirloom. The story could start with an old family's most prized possession disappearing overnight. The main character, a young detective, could be hired to solve the mystery. He or she then discovers strange footprints around the scene and some cryptic notes left behind.
One idea could be a story about a lost little puppy. The puppy wanders away from its home and meets different animals in the forest. It could meet a friendly squirrel who tries to help it find its way back. The puppy then has an adventure with the squirrel as they search for the puppy's home.
One idea could be a murder in a small, isolated town where everyone seems to have a secret. The victim is a newcomer who might have uncovered something that threatened the town's hidden past. For example, a long - forgotten crime or an illegal business operation. Another idea is a murder at a high - society party. The guests are all wealthy and powerful, and any one of them could have a motive, like jealousy over a business deal or a love affair. A third idea is a murder in a spooky old mansion. There could be hidden passages and rooms, and the killer uses the layout of the mansion to their advantage to commit the crime and then disappear.
You could have a murder mystery where the victim is a journalist who was about to expose a big scandal. The killer could be anyone from a corrupt politician to a powerful business tycoon who wants to keep their secrets hidden. It would be interesting to see how the detective tries to uncover the web of lies and cover - ups.
What about a horror mystery on a deserted island? A shipwrecked group of people find themselves on an island that seems normal at first. But then they start noticing strange markings on the trees, and members of the group start disappearing one by one. It turns out that there's a hidden tribe on the island that has been sacrificing outsiders for decades to appease their bloodthirsty gods.
One idea could be a murder in a small, seemingly idyllic town. The victim is a local shop owner. The detective discovers that the motive is related to a long - hidden family secret. Years ago, the shop owner's family had cheated another family out of a valuable piece of land, and the killer is seeking revenge for that injustice.
A murder occurs in a theater. The victim is an actor. The killer could be a jealous understudy who was constantly overshadowed by the victim. The understudy saw an opportunity when the actor was alone backstage and struck. The detective finds out by looking at the understudy's rehearsal schedule which shows they had ample opportunity to plan the murder.