The Lost Notebook is a celebration of film escapism. Through 52 years an ordinary factory worker meticulously wrote down his 2158 cinema visits in communist Hungary. When the Danish director Ida comes across the discarded cinema diary, she embarks on a journey to unravel the author's profound passion. In present-day Hungary Ida meets a family divided by secrets and past traumas but who share a very special love for films - particularly action movies. Using clips from the titles in the cinema diary, the film illustrates the family members' inner dreams and longings. What is cinema if not merely an escape from the harsh reality: A way to travel, to find justice or to keep a family together?