Sara Dixon, Teen Detective (Dominoes Readers)

Sara has exams to study for, but too much is going on! A girl from her school is dead, something is strange about her boyfriend Luke, and her friend Carlie is keeping secrets. Is it all connected? Sara tries to find out what's happening. She's a top student at school, but she's going to have to break a few rules if she is going to learn what's happened to Luke. Can she solve the mystery before it's too late?