The Secret Society of Souptown (2015)

"Secret Society of Souptown" is an adventurous family movie that takes place in Souptown, a district in the summery city of Tartu. Four children - Mari, Sadu, Olav and Anton form a secret society to play hide-and seek games invented by Mari's grandfather, a professor at the university. When the city is attacked by a mysterious poison which turns adults into children our gang embarks on a quest for the antidote. Their path is paved with challenges bigger than any other they have seen so far. It is an adventure you cannot even imagine... Will the children find the antidote in time to save their loved ones.