E. E. ‚Doc‘ Smith 
Second Stage Lensmen [EPUB ebook] 

Kim Kinnison was Number One of his time. To him fell the incredible assignment of infiltrating the inner circle of Boskone. Kinnison’s deadly job was to become a loyal Boskonion in every gesture, thought, and deed. He had to work himself up through the ranks of an enemy alien organization, into the highest echelons of power – until it was he who would be issuing the orders that would destroy his own civilization!