Looking for a completely free PDF of 'Broken Knight' legally is tricky. Straight up, you probably won't find the full novel free from a publisher or author site, unless it's part of a short-term promotional offer. They want you to buy the book or read through subscription services.
Your best legal bets for access are library apps like Libby or OverDrive. You link your real library card, and if your library has purchased a digital copy, you can borrow the EPUB, which is essentially the same as a PDF for reading. It's not a permanent download, but it's free and legal while you have it checked out.
You might also find a free sample or the first few chapters through retailers like Amazon Kindle, Apple Books, or Google Play Books. Publishers often offer those to hook readers. But for the whole thing, free usually means library or a very generous author website giveaway.