To start writing a puzzle mystery novel, you need to have a clear idea of the mystery you want to present. You can draw inspiration from real - life events or other mystery stories. After that, develop a plot structure that gradually reveals the mystery. Begin with a hook to draw the reader in, like an unusual discovery. Then, as you write, make sure to include red herrings, false clues that mislead the reader, to make the puzzle more complex. And don't forget to have a satisfying resolution at the end where all the pieces of the puzzle fit together.
First, come up with an interesting mystery. It could be a missing object, a strange disappearance, or a murder. Then, create characters who are involved in the mystery in some way. Next, start planting clues throughout the story. These clues should be subtle at first. For example, a character might mention something in passing that later turns out to be a key piece of the puzzle.
Begin by choosing a setting for your mystery. It could be a small town, a big city, or an isolated place like an island. The setting can play an important role in the mystery. Then, think about the characters' motives. Why would they be involved in the mystery? Is it for money, love, or revenge? Once you have these elements, start building the puzzle. Drop hints about the mystery in the characters' dialogues, their actions, and the descriptions of the setting. As you progress, keep in mind that the reader should be able to piece together the mystery by the end, but not too easily.