Someone to run with - David Grossman

Earnest, awkward and painfully shy, sixteen-year-old Assaf is having the worst summer of his life. With his big sister gone and his best friend suddenly the most popular kid in their class, Assaf spends his days at a lowly summer job in Jerusalem City Hall and his evenings alone, watching television and playing games on the Internet. One morning, Assaf's routine is interrupted by an absurd assignment: to find the owner of a stray yellow labrador. Meanwhile on the other side of the city, Tamar, a talented singer with a lonely, tempestuous soul, undertakes an equally unpromising mission: to rescue a young drug addict from the Jerusalem underworld
and, eventually, to find her dog.