John Allison 
Bad Machinery Vol. 4: The Case of the Lonely One [PDF ebook] 

A new school year brings a new classmate to Griswald’s Grammar School! But he’s a bit strange, and he really, really likes onions. When the whole school suddenly becomes best friends with him, Shauna seems to be the only one left out. It’s up to her to peel back the mystery, one onion layer at a time.Join the team for another thrilling case, full of the cunning wit and high-flying adventure you can only get from John Allison’s BAD MACHINERY.