Quantum Field Theory in Curved Spacetime: Quantized Fields and Gravity (Cambridge Monographs on Mathematical Physics) 1st edition by Parker, Leonard, Toms, David (2009) Hardcover
One of the best book on the topic, covers everything in the pedagogical order. Covers almost everything but just lacks in the segment where it couldn't argue why exactly is it that, the definition of particle is ambiguous in curved spacetime, apart from that everything else is here. I wanted a single source, where I could everything that was relevant to this field, so that perhaps in the future i would be able to understand the research done in this area.