Bad influence - William Sutcliffe

Ben and Olly are best friends, and it's Ben who tells the story of what happened that autumn, starting right at the end of the summer holidays:
how Carl moved into the street and everything changed forever. Because Carl was different: he talked back to grown-ups, he skipped school, he played games with knives and matches. And he had moments when he looked strange and you never knew what he was going to do. William Sutcliffe's chilling new novel, narrated by the 10-year-old protagonist, describes what happens when a stranger disturbs the balance of a delicate childhood friendship.