Doctor Stephen Strange is one of the foremost authorities in neurosurgery, with an ego and arrogance to match his unparalleled skill. Unfortunately, while driving to give a speech one fateful evening, Doctor Strange find himself in a harrowing car accident which damages the nerves in his hands to such a degree that the precision and finesse that made him a master surgeon was gone. Unable to accept that he could never practice his trade again, Doctor Strange goes to extreme lengths to find a means to heal his hands, driving himself into financial ruin.
Eventually, Doctor Strange learns of Jonathan Pangborn, a quadriplegic who miraculously regained the use of his arms and legs. Doctor Strange seeks out Pangborn, who explains that he owes his regained mobility to the mystic arts learned from a mentor simply known as the Ancient One, in Kamar Taj. Doctor Strange, with all other options exhausted, decides to pursue this lead.
Doctor Strange uses the last of his money to travel to Nepal, his search for Kamar Taj leading him to Mordo, one of the Masters. Mordo brings Doctor Strange for an audience with the Ancient One, who shatters Doctor Strange's skepticism with magic, showing him the existence of parallel dimensions separate from the reality he knows of. Doctor Strange begs the Ancient One to teach him. She refuses. After ultimately relenting, the Ancient One takes him in and teaches him to become a sorcerer.
Doctor Strange learns that the universe as he knows it is protected by three Sanctums; centers of magical power in New York, Hong Kong, and London that stave off the influence of Domammu, the Dark Dimension incarnate. It is the task of the Masters of Kamar Taj to protect the Sanctums. In time, Strange becomes increasingly adept in the mystic arts, but also increasingly curious; he sneaks in and experiments with the Eye Of Agamotto, an artifact that can help a sorcerer to manipulate the flow of time. When he is saved by Mordo and fellow Master Wong, he is warned about the dangers of tampering with time, as it could have disastrous consequences for him.
A group of sorcerers, led by the rogue pupil Kaecilius, who took some pages from one of the Ancient One's own tomes in Kamar Taj, hope to summon forth Dormammu, the Dark Dimension, for eternal life, as he is a realm where time did not exist. The plan slowly advances as he and his fellow sorcerers destroy the London Sanctum, weakening the universe's protection against the Dark Dimension. They then attack the New York Sanctum, killing the Master guarding it, but Doctor Strange, along with the sapient Cloak Of Levitation, fend them off. During the battle, however, Kaecilius reveals that the Ancient One owed her immortality to stealing power from Dormammu, the Dark Dimension. She is mortally wounded in the battle, and the Ancient One tells Doctor Strange that rules may need to bend in order to protect their world.
Doctor Strange reaches Hong Kong, where Wong laid dead and the Sanctum laid in ruins. With the Dark Dimension encroaching on Earth, the situation has grown dire, and time is running out to save the universe.
...or so it seems. With the Eye Of Agamotto, Doctor Strange turns back the clock on Wong and returns him to life. He then reverses the destruction of the Hong Kong Sanctum as he, Mordo, and Wong battle Kaecilius and his followers.
Gradually, Kaecilius and his followers seem to be over-powering Doctor Strange, Mordo, and Wong. However, an off-hand remark about the blessings of Dormammu, that the Dark Dimension is a place beyond time, gives Doctor Strange an interesting idea. He travels directly to the Dark Dimension to confront it:
"Dormammu...I've come to bargain!"
The ensuing battle ends all too quickly, with Strange dead. Not long after, however, Strange returns...
"Dormammu, I've come to bargain!"
Dormammu is perplexed at how Strange was standing before him again, making the same demand, and kills him once again. Moments later...
"Dormammu, I've come to bargain."
And so it goes, with Dormammu killing Doctor Strange again and again, only for Doctor Strange to return and repeat his demand. Doctor Strange explains that he used the Eye Of Agamotto to cast a spell that introduced Dormammu, the Dark Dimension, to the concept of time, by trapping them both in an endless loop that restarts every time Strange dies. In so doing, he knowingly subjects himself to a potential eternity of painful demises, but Earth would not be encroached upon further by the Dark Dimension; a sacrifice Strange is willing to make.
The endless cycle of Doctor Strange coming to bargain, dying at Dormammu's hands, and coming back to bargain eventually becomes too maddening for Dormammu to bear, and he finally agrees to listen to Doctor Strange's demands; if Dormammu would stop encroaching on Earth and take Kaecilius and his apostles away with him, and not threaten his universe any further, Doctor Strange would break the cycle.
Dormammu agrees, and the encroachment on Earth is reversed. Kaecilius and his underlings are taken away to Dormammu, the Dark Dimension, and Earth is spared certain destruction. Doctor Strange becomes Sorcerer Supreme of Earth, residing with Wong in the New York Sanctum Sanctorum, keeping vigil over the multiverse, continuing his studies, and offering his services to those seeking them, such as Thor, arrived with Loki looking for their father on Earth...
Not all is well, however: Mordo has grown disillusioned after seeing how the Ancient One and Doctor Strange repeatedly violated what he called "the natural law" to save the multiverse. Having decided that there are "too many sorcerers", he has begun to hunt down others, starting with Pangborn...
