Neil Clarke is a disillusioned, cynical London secondary school teacher whose life is drifting aimlessly. Harboring secret ambitions to be a
science fiction writer, he is trapped in a mundane routine, hopelessly pining for his downstairs neighbor, the vibrant and attractive aspiring documentary filmmaker, Catherine. Neil’s existence takes a cosmic and chaotic turn when a tribunal of omnipotent, arrogant extraterrestrials from the Galactic Council decide the fate of Earth. To determine whether humanity should be eradicated as a worthless plague or spared to join the galactic community, the aliens randomly grant a single human absolute free will—the power to do absolutely anything with just a wave of the hand.Neil is chosen for this ultimate test. Unaware of the cosmic stakes, he soon discovers his new godlike abilities when minor annoyances vanish and impossible events occur at his whim. Initially, Neil uses his powers for petty, mundane desires. He makes a barking neighborhood dog fly into outer space, causes a rude commuter to strip naked, and forces his shallow headmaster to resign. However, as the novelty wears off, Neil begins to use his gift to improve his daily life and win Catherine's affection. He resurrects her deceased dog, makes himself irresistible to her, and even commands world leaders to achieve world peace and end global hunger.Yet, Neil's profound ignorance of the rules leads to catastrophic
unintended consequences. Because he cannot undo death or force people to genuinely fall in love, his selfish commands backfire. When he wishes for millions of pounds, the money crashes through his ceiling and buries him. Desperate to win Catherine’s genuine heart without manipulation, he stumbles when his spiteful wish to make an obnoxious suitor, Ray, "disappear" results in Ray turning into a dog, straining Neil's relationship with Catherine.Meanwhile, the cynical Galactic Council grows bored by Neil’s human limitations and mistakes, preparing to push the big red button to destroy Earth. Realizing the end of the world is imminent, Neil hatches a final, selfless plan. With Catherine still grieving and the aliens preparing to vaporize the planet, Neil uses his absolute last wish to grant ultimate intelligence and free will to his loyal, talking dog, Dennis. Because Neil cannot wish himself dead, he commands Dennis to wish that Neil never received his powers in the first place, sacrificing his own godhood to save humanity. The universe resets, Neil loses his powers, but he retains his memories of Catherine. Impressed by this ultimate act of selflessness, the aliens spare Earth, and Neil finally wins Catherine's love naturally, embracing a humble, happy life.