An alien (Aamir Khan) lands on earth and gets robbed on the very first day of his voyage. Though, he came on earth entirely naked just like a new-born baby, yet he had the precious gadget which was his only mean to head back to his own planet, which has now been robbed. His antics gain him the name of "PK" from the habitats of earth.

In the quest of finding the robbed property, PK earns the friends of life in Bhairav Singh (Sanjay Dutt) and Jagat Janani aka Jaggu (Anushka Sharma). Through his child-like curiosity, he challenges the spiritual odyssey and raises the curtains from religion and godmen.