Troll Vasya in the Leningrad Zoo, or The Schemes of Trollingda

Troll cub Vasya still cannot pass the exam in mischievous pestering. His family moved for the summer from under the Anichkov Bridge to the Petrograd Side, living not far from the zoo — and Vasya and Vasilisa spend a lot... of time there. One day, Vasya and Vasilisa observe a strange sight: a helicopter is rising from the side of Peter and Paul Fortress, with a long neck of a giraffe sticking out of the window. The friends think that it's just their imagination due to the heat. But the next morning, Vasilisa learns from her grandmother that all the newspapers are reporting on the disappearance of some animals from the zoo. Vasya and Vasilisa decide to conduct their own investigation...