Full story
In Kathmandu, the sorcerer Kaecilius and his zealots break into the library at Kamar-Taj, kill the librarian and tear pages out of a forbidden book that belongs to the Ancient One. She chases them, but they get away.
In New York, Stephen Strange is a brilliant, unbearable neurosurgeon. One rainy night he loses control of his car and wrecks his hands. Unable to operate, he burns through his money on experimental surgeries and pushes away even Christine Palmer, the colleague trying to help him. He hears about Jonathan Pangborn, a paraplegic man who walks again, and Pangborn points him to Kamar-Taj in Nepal. There, the Ancient One knocks Strange out of his body and shows him other dimensions. She hesitates, because his ego reminds her of Kaecilius, but agrees to train him.
Strange learns fast. With Mordo and Wong, he studies spells, shields and portals, and learns that three Sanctums, in New York, London and Hong Kong, shield Earth from threats from other dimensions. In secret, he uses the Eye of Agamotto to bend time, which annoys Mordo and Wong. Meanwhile, Kaecilius uses the stolen pages to reach Dormammu, ruler of the Dark Dimension, and destroys the London Sanctum.
Kaecilius hits the New York Sanctum, and Strange, who lands there by chance, holds him off with help from the Cloak of Levitation. In the next fight, the Ancient One is fatally wounded. Strange learns she drew power from the Dark Dimension itself to live for centuries. Before she dies, she talks to him on the astral plane and says Strange and Mordo need each other.
In Hong Kong, the Sanctum has already fallen, Wong is dead and the Dark Dimension is swallowing the city. Strange uses the Eye to turn back time, saves Wong and goes into the Dark Dimension. There he traps himself and Dormammu in a loop, dying over and over and always returning to the same moment. Worn down, Dormammu takes the deal, leaves Earth and takes Kaecilius and his followers with him. Mordo, disgusted that Strange and the Ancient One broke the laws of nature, walks away from the sorcerers. Strange moves into the New York Sanctum. In the mid-credits scene, he agrees to help Thor find Odin. In the final scene, Mordo strips Pangborn of his powers and says the world has too many sorcerers. That thread is left open.

