After 70 million star cycles, the Nitolans' star fleet returns to its beloved planet, only to find that its name is now Earth and its dominant race has evolved from what the dinosaur-like Nitolans knew as a kind of edible tree squirrel. When the Nitolans request a parlay, the only available US envoy who is both able to fly a space vehicle and who is trained in public relations is Carl Baxter, ex-astronaut-turned-adman. Baxter learns the worst: the Nitolans have a Power that can cauterize Earth so that they can start over. But after examining Earth's computer records, they decide to leave--explaining that at the present rate humankind will wipe itself out in 200 years anyway. Earth may have learned from the encounter, however--and the Nitolans may be changed by that strange human trait, ""humor."" This alien-contact yarn may be the best story yet in the Millenium series. Human and Nitolan idiosyncrasies ring true; even the open-ended resolution seems as likely as not. In an endearing scene at the end, a five-fingered dinosaur breaks into giggles at a joke: ""Why are a little grey mouse and Santa Claus similar?. . . They both have long white beards, except for the mouse."" Learning what makes the funny could even improve relations between alien groups like children and grownups here on Earth.