On May 22, 2018, every person on Earth sneezes. Simultaneously.
Hours later, an alien spacecraft appears over New York City and broadcasts a dire message of impending doom. The future of the human race will depend on the whims of a solitary extraterrestrial who appears in the form of Walter Cronkite. Yes, that's right, Walter Cronkite, the deceased news anchor.
The alien has some nasty surprises for the residents of Earth, and the race is on to figure out his true motives and the meaning of the sneeze event--before it's too late.