Strange Stories About Space

I received a strange anonymous letter that day. Because of that letter, I time-traveled into the horror novel I wrote. There were five people traveling with me. They were a doctor, a female college student, a bartender at a bar, an employee in the company, and a young private detective. I couldn't help but look at why these people time-traveled together into the novel, until they told a surprising story. It's a big secret. They all received the same anonymous letter, and the content in it was related to the novel I wrote. The letter said: "Do you believe there is another dimension in this world? There is a group of mysterious creatures in that dimension that no one has ever seen. Maybe they don't exist, and maybe you don't exist either. If you want to know the truth... "Alien Space" will find the answer..."