A short and curious work recounting an extremely vivid and elaborate vision while under the influence of morphine. The tale seems to be based on a true story, an experience of the author John Cunningham who explains in a "Letter to My Friends" that "Although requested by a number of you at various times to write this condensed narrative of an event in my life, associated with much misfortune, sadness and suffering which have continued for some years, it was not until during a lonely period of quietude at Brooklyn, N.Y., in the summer of 1872, that I made the effort." The tale, told in the third person, begins with a short preface telling how Cunningham came to tell his story:

The peculiar and startling effect of morphine on a person unaccustomed to its administration, was happily illustrated in the instance of a gentleman to whom, under its influence, (about three eighths of a grain,) the dream to be related occurred. This individual, (a South Carolinian resident on a plantation,) a few years ago, had lately received a severe and extensive burn, which confined him to his bed six months. An allusion by him in a casual conversation in the city of New York recently to the eventful dream and its circumstances, brought out a solicitation to him to write its narrative, which in substance he here gives.

Cunningham's narrative then beings proper:

The sleep was serene, the mind active, and the dream promptly and vividly supervened. A being in the form of a handsome and matured man, full of esprit, in a white and easy-fitting garment, with bright, broad and sweeping wings coming out from each side of his back below the shoulders, appeared to the patient at his bedside, and announced to him that he was the Spirit of Morphine, of a heavenly and immortal nature, and that he had come to carry him on an aerial voyage over many parts of the world, to show him many attractive regions and things, to introduce him to various races, royal personages, distinguished celebrities, etc.

The morphine-addled "Sleeper", as he is referred to throughout, then proceeds to accompany the "Spirit" on a long and winding flight witnessing a range of strange and marvellous natural phenomena - such as a window at the North-pole down into the fiery core, and 500 foot primordial lizards - as well as a whole host of spiritual and philosophical encounters with the likes of Confucius, Cleopatra, and Zoroaster.