In a world not so unlike ours, immortality is treated as a miraculously rare but real phenomenon that upturns lives of all those that come in contact with it. No known cause or pattern of occurence has been discovered but when any one person acquires it there is sure to be a sudden massive loss of lives at the same time. In some cases these new immortals can be found all alone in the middle of a newly dead city and in others death simply takes any number of victims in any corner of the globe.
Other than no longer being able to age, die or get hurt, these immortals show no measurable abnormalities in physiology when tested - their bodies simply refuse to move forward in time. With seemingly nothing to be learnt from them, these immortals are regarded as survivors of mysterious spontaneous calamities and those that remain will have their own spectrum of views on how they should be treated. Some take advantage of these unfortunate souls building whole systems around them while others reject them outright as though they were walking plagues. Whatever the case may be in any particular place and time, the world will no longer be as kind to them as it had been back when they could die.
The story follows the travels of the "Doctor", a legend that is puported to be capable of helping the immortals with their troubles. Nearly as mysterious as the phenomenon itself, the figure in question seems to be armed with knowledge and tools beyond the comprehension of even the most reputed experts on immortals. His existence is recorded in rare pieces of history dating back centuries and whenever historic event involving an immortal takes place he is sure to have been involved in some manner. Disappearances of immortals are attributed to him being in possession of a "cure" for the blight of immortality and that notion grants hope to both immortals and mortals alike. The truth behind the immortals and this medicine man of theirs unravels in bits and pieces but will the picture that forms out of them be one they can live with?
The twist is that the "Doctor" is not a single immortal being but a legacy inherited and succeeded by his believers.