Allan Quatermain, following his 'death,' returns to his friend, Lady Ragnall, to partake of the taduki drug she has. One point of interest is the fact that, though Quatermain only faked his death, he no longer has a shadow (at least during the first part of the Sundered Veil), as shown on the picture in which he is greeted by Lady Ragnall's servant (he seems to retrieve it when entering the Sphinx, though). Quatermain takes the drug and enters into a dream-world, encountering the equally-lost John Carter and his grand-nephew, Randolph Carter. Strange creatures begin to attack them but they are saved by the arrival of a pulsing electric machine piloted by a man known only as the Time Traveller.
They arrive at the Sphinx, and the Time Traveller explains that they are there because creatures from beyond the universe are invading creation through a hole in space-time. They are attacked by albino creatures, known as both Morlocks and Mi-go. Quatermain beats them off as the time machine takes off, but one clings on and damages the ship. Destabilized, the time machine is drawn towards a "chrono-crystal aleph" and the riders all see visions from their pasts and futures.
Quatermain sees his first meeting with Mina Murray from the first League issue; a sojourn with Sir Henry Curtis; the final battle against Professor Moriarty's ship from the end of the first League volume; Mr. Hyde's destruction of a Martian Tripod from the end of the second League volume; and he, Randolph, and Mina's encounter with a Lovecraftian monster as related in The New Traveller's Almanac. Randolph sees a vision of Arkham. John Carter sees a vision of him fighting a Green Martian and winning Dejah Thoris as she rides a Greater Thoat mount.
Randolph and John soon disappear to their visions upon realizing that they're not bound to their realm, leaving only Quatermain to help the Time Traveller against their enemy. However, Quatermain becomes possessed by Ithaqua (the Cthulhu Mythos incarnation of the Wendigo) and returns to his realm. He kills Lady Ragnall before her African servant, Marisa, is able to free Quatermain using her tribe's precautions against the Great Old Ones. Appalled, Marisa flees the burning manor, taking the taduki with her.
Despondent at the loss of his friend and his drug, Quatermain spends the next few years drifting, eventually ending in Cairo. The story ends with him looking up from his drugged stupor into Mina Murray's face as he is unwillingly - but fatefully - recruited into The League of Extraordinary Gentlemen.
Among the characters the story takes place at various points in their lives:
- Allan Quatermain: after his 'death' in Allan Quatermain but before the first League volume
- Randolph Carter: during his titular dream quest in The Dream-Quest of Unknown Kadath
- John Carter: after his departure from Earth but before his arrival at Mars in A Princess of Mars
- The Time Traveller: following his return to the future at the end of The Time Machine