Here are my favorite intelligence and espionage books:

Spies, Lies, and Algorithms: The History and Future of American Intelligence, by Amy Zegart

Critical Thinking for Strategic Intelligence by Katherine and Randolph Pherson

DFIR Investigative Mindset by Brett Shavers

Intelligence: From Secrets to Policy, by Mark Lowenthal

Structured Analytic Techniques for Intelligence Analysis by Randolph Pherson and Richards Heuer