Ep 2. Smile

The Doctor (Peter Capaldi) and his new companion, Bill (Pearl Mackie), land on a distant planet that humans colonized centuries ago, only to find the place deserted. They soon discover that deadly robots have infiltrated the planet, and the pair must use their wits to survive. The robots are supposed to maintain happiness for the colonists, but they have interpreted that directive quite literally. The slightest sadness can cause them to attack, leaving the Doctor and Bill in a perilous situation. To make matters worse, the planet's power source is failing, and the robots are starting to glitch. The Doctor must figure out a way to fix the power source and stop the robots before it's too late. Along the way, he and Bill confront some tough ethical questions about the limits of artificial intelligence and the nature of happiness. Smile is a classic Doctor Who adventure featuring high stakes, complex moral quandaries, and a good amount of humor.