Quantum Field Theory by Peskin and Schroeder. There are many things in that book I could make into a standalone project that could occupy years at a time.
Some other picks:
The Man in The High Castle by Phil K. Dick. The Plague or The Outsider by Albert Camus. City of Thieves by David Benioff.
Some other picks:
The Man in The High Castle by Phil K. Dick. The Plague or The Outsider by Albert Camus. City of Thieves by David Benioff.