The Man on the Balcony (The Martin Beck series, Book 3)

The third book in the hugely acclaimed Martin Beck series: the novels that shaped the future of Scandinavian crime fiction and influenced writers from Stieg Larrson to Jo Nesbo, Henning Mankell and Lars Kepplar.
Someone is assaulting and killing young girls in the once-peaceful parks of Stockholm. Detective Inspector Marin Beck has two witnesses: a cold-blooded mugger who won’t say much, and a three-year-old boy who can’t say much. The killer will strike again, and the police are getting nowhere. Can Beck crack the case before time runs out?