Four kids – Markus, Emilia, Rosanna and Karl – spend together their summer holiday in a sleepy resort town Haapsalu. The holiday has had a boring start but suddenly things take an unexpected turn and the four friends find themselves in the middle of a huge adventure. The stolen clocks from the local antique shop, presence of famous photographer Stig Velson in Haapsalu and the historical events that took place in the local bishop's castle in 15th century – all this might be connected. The four novice detectives have to solve a complicated mystery of clock robbery and to find the treasure including the instructions of making gold that has been lost for centuries. The adventure includes cheaters, policemen and the ancient legent about the White Lady.