I get asked this a lot by friends who want to save money but don’t want to step into shady territory. If you mean the book titled 'Thirst', the short, practical truth is: only sometimes. Official sites will offer a free PDF only if the rights holder (author or publisher) has explicitly released it. So I always start at the obvious places: the author's official website, the publisher's site, and any official newsletter or social post from them. Authors occasionally do free PDF giveaways, sample chapters, or full downloads for promotional runs, especially for indie titles.
If you don’t find it there, check legitimate library or academic options next. Services like OverDrive/Libby, your public library’s digital collection, or the Internet Archive/Open Library sometimes provide legal loans of full ebooks and PDFs. For older works that are in the public domain, Project Gutenberg or HathiTrust can be golden. Avoid sketchy “free download” sites that don’t list rights — they often host pirated copies and can carry malware. Personally, I’d rather wait for an official free release or borrow it legally; it keeps my conscience and my laptop safe, plus it actually supports the people who created the work.