In the fourth book of the series, Haylie, Rachel, and Kayla Van Duren take on their biggest case yet. It is April, and so the girls start with a family April Fools tradition in which one sister must put together clues to find out who belongs to what April Fools prank. But that is just the beginning for this mystery-packed fourth book. While at the National Law Enforcement Convention, their mom calls home with a case so big that not even the best detectives in Texas can crack it. The question is, will the Van Duren girls be able to solve the first national case ever?