The Dark Tower is an incomplete manuscript written by C. S. Lewis that appears to be an unfinished sequel to the science fiction novel Out of the Silent Planet, though allegations have been raised about its authenticity. Perelandra instead became the second book of Lewis' Space Trilogy, concluded by That Hideous Strength. Walter Hooper, Lewis' literary executor, titled the fragment and published it in the 1977 collection The Dark Tower and Other Stories. The Lewis scholar Kathryn Lindskoog challenged the authenticity of the work. Plot summaries The story deals with an early rendition of interdimensional travel. A fictional Lewis himself narrates, as he does in Perelandra, but Elwin Ransom appears as a supporting character. The story begins with a discussion of time travel among several academics at a university (subsequently identified as Cambridge) during summer vacation. They conclude that it is impossible to violate the laws of space-time in such a way. However, after the discussion, one of the men (Orfieu) unveils an invention he believes allows people to see through time. The group uses this "chronoscope" to observe an alien world they call "Othertime" (he does not know if it is future or past), where a group of human automatons work to construct a tower at the bidding of the story's villain, the "Unicorn", a devilish but human (or possibly semi-human) character with a single horn growing out of his forehead. The Unicorn stings people, apparently volunteers, causing them to become automatons (the "Jerkies"). After a while MacPhee, a character who appears in That Hideous Strength (though here he is a Scot, not an Irishman), points out that the "Dark Tower" is in fact a replica of the new Cambridge University Library. This suggests Othertime is the far future, with a replica of an ancient monument being constructed. It is discovered that Orfieu's assistant, Scudamour, has a double in Othertime. Increasingly, the observers wonder if Othertime really is the past or future, or whether it is some other reality. Scudamour's double grows a sting and becomes the new Unicorn. During one viewing session, Scudamour sees the Unicorn about to sting the double of his fiancée, Camilla. In a blind fury, he rushes at the screen, and somehow switches bodies with the Unicorn. The remainder of the text deals with his experiences in Othertime, as well as his colleagues' attempt to hunt down the Unicorn in this world. In Othertime,