Koko and his friends are spending summer vacation on the shores of a lake near the idyllic Green Hill, hanging out and playing. The magical countryside is disturbed by unusual events which alarm the children as well as the locals: under cover of night, burglars break into one house after another. When the police turns a blind eye to denunciations by adults, the children decide to take matters into their own hands and unmask the burglars.
Unfortunately the movie The Mystery of Green Hill is not yet available on HBO Max.
| Production | Ankica Jurić Tilić | Producer |
| Production | Hrvoje Pervan | Producer |
| Camera | Danko Vučinović | Director of Photography |
| Editing | Slaven Zečević | Editor |
| Writing | Hana Jušić | Writer |
| Sound | Dinko Appelt | Original Music Composer |
| Writing | Ivan Kušan | Novel |
| Directing | Čejen Černić | Director |
