I find that there are very few YA mysteries. The only book that comes to mind is No One Else Can Have You by Kathleen Hale. Now I can add A Trouble Is A Friend of Mine. Here a quick summary from Goodreads: The first time Philip Digby shows up on Zoe Webster’s doorstep, he’s rude and he treats her like a book he’s already read and knows the ending to. But before she knows it, Zoe’s allowed Digby—annoying, brilliant, and somehow…attractive? Digby—to drag her into a series of hilarious, dangerous, and only vaguely legal schemes all related to the kidnapping of a local teenage girl. A kidnapping that might be connected to the tragic disappearance of his little sister eight years ago. When it comes to Digby, Zoe just can’t say no. But is Digby a hero? Or is his manic quest an indication of a desperate attempt to repair his broken family and exorcize his own obsessive-compulsive tendencies? And does she really care anyway? Zoe is a relatable voice, who keeps the story as realistic as possible, while Digby adds a quirky touch to the novel. Overall the story kept me interested by sprinkling twists here and there. Some of the dialogue in the story made me laugh out loud, literally. Trouble is a Friend Of Mine is a cute read that I would recommend to anyone who likes humorous, coming of age, or quirky books.