Diplomatic Immunity

"Diplomatic Immunity" by Robert Sheckley is a science fiction story where Earth faces an unusual predicament: an alien ambassador arrives with an invitation to join a vast galactic empire, but this ambassador can turn into whatever poses a threat, making him seemingly invincible. Colonel Cercy and a group of scientists find themselves in a desperate race against time, trying everything from advanced weaponry to mind games to stop the ever-adapting alien. They discover that the ambassador's power comes from a deep understanding of chaos, leading them to devise special tools that disrupt this very principle. In a climactic showdown of wits and technology, they manage to defeat the ambassador, saving Earth from being taken over, in a tale that blends humor with serious questions about power, resistance, and what it means to be intelligent.