A formidable problem (e.g., the file is encrypted with a password that only a dead person knew).

Consider writing in the third person to make the synopsis and world-building clearer [4].

A "proper" story needs conflict and stakes [15]. Ensure your protagonist faces a real struggle to sort out the mystery of the ZIP file. Once the draft is done, revise and edit to polish the language and fix any subplots that distract from the main mystery [1, 12].

Decide if this is a modern-day tech thriller or a futuristic sci-fi. Use the setting to transport the reader emotionally [6].