Every living creature on Earth strives to find the Door to Summer. Where it is warm, there is no cold, no war, hatred, resentment. Where your friend will not betray you, your bride will not deceive you. In the famous novel by Robert Heinlein, such a Door to Summer is sought by Daniel Boone Davis and his cat Petronius Arbiter, a completely polite animal – when he is not petted against the grain and not patted on the back. To find the Door to Summer, the cat and his owner have to overcome Time, and Time has a harsh disposition – it is not ready to play games with everyone, preferring those whose hearts are open to the world.