The Door into Summer is a science-fiction movie based on the novel of the same name by Robert A. Heinlein. The movie follows the story of a roboticist named Daniel Boone Davis, who awakens from his cryogenic slumber in 2025 after being frozen for decades.
Davis discovers that his beloved sister, who had adopted him as a child, has passed away, and her only daughter has been taken away by an abusive husband. Davis realizes that he must go back in time to 1995 to save his niece and prevent his sister's death.
With the help of his colleagues, Davis creates a time machine called "the Door into Summer," which takes him on a journey to 1995. Once there, he uses his advanced knowledge of robotics to create a humanoid robot named "Hired Girl" to protect his niece and also manages to prevent his sister's tragic fate.
However, when Davis returns to 2025, he realizes that changing the past has unanticipated consequences, and he must undertake a dangerous journey to try and fix the timeline and ensure a better future for himself and his loved ones.
The Door into Summer explores themes of time travel, family, and sacrifice, offering a gripping and thought-provoking tale that leaves the audience eagerly anticipating the fate of its protagonist.