11-year-old Nisse Berg lives a life of bad luck. His mother, Sara, is no longer with him, but before she died, she gave him a pet lizard. The lizard is boring and ugly. Nisse thinks it looks like a grumpy old man and calls it Harry. But suddenly one day, Harry the lizard begins to talk. He tells Nisse that he is a dragon with a dragon heart, and that Nisse also can get a dragon heart if he wants to. The film is based on the book Syltmackor & oturslivet from the series Drakhjärta by Anna Ehring.