The best mystery that I have read would be “ The Oblong Crate”. I like this mystery because the writer kept you guessing what was in the crate. When he came up with an explanation it seemed like it could be the answer but when it wasn’t you wanted to know what it was.
My story starter: Ahhhhh! When 13 year old Julia went into her room it had been trashed. Her computer and television was gone! Her mom walked in and then said she would call the cops. When they arrived they asked her mom a lot of questions. It did not help them any because they found out that she had an alibi, she had been at work all day with many witnesses. They did get one clue though. There was squashed mud with a perfect boot print. The person had left in hurry not to cover up their tracks.