premise: Hard Landing is a 2004 thriller novel by British author Stephen Leather. Published in 2004 by Hodder & Stoughton, it is the first book in the Dan ‘Spider’ Shepherd series. "Hard Landing" is an international bestseller and is available in ebook and paperback.
hypothesis: There were other books to follow after Hard Landing was released. 
reason: it says that Hard Landing was the first book in the series so there are others that follow but the wording indicated to the AI that it was neither.