Mystery Mansion (1983)

Susan and her brother Johnny go to spend the summer with their aunt and uncle, where they discover a map that may lead to some sort of treasure. Susan had been having nightmares about a girl, Rachel, who disappeared in a nearby mansion, now old and abandoned. Eventually, Susan and Johnny, along with their cousin Billy, begin a quest to find the treasure, as well as the answers to Rachel's disappearance. While they are doing this 2 escaped convicts are also looking for the same treasure!