It is a sequel to the original volume of The League of Extraordinary Gentlemen and like its previous installment is a pastiche of various characters and events from Victorian literature; though it borrows a great number of characters and elements from various literary works of writers such as Sir Arthur Conan Doyle, Edgar Rice Burroughs, Ian Fleming, Robert Louis Stevenson and Bram Stoker, it is predominantly a retelling of The War of the Worlds by H. G. Wells.

The volume continues the narrative of Mina Murray, Allan Quatermain, Hawley Griffin, Dr. Henry Jekyll/Edward Hyde and Captain Nemo who respond to an invasion of England by extraterrestrial invaders.

On Earth, in the year 1898, the League of Extraordinary Gentlemen (consisting of Allan Quatermain, Dr Henry Jekyll, Mina Murray, Captain Nemo and Hawley Griffin) arrive in Horsell Common, where a Mollusc spaceship lies at the centre of an impact crater.

As the heat-ray kills the onlookers gathered around the crater's edge, Dr Jekyll turns into Mr Hyde, who threatens the alien with violent death.

Later that day, the British armed forces arrive in the area, and Griffin sees another spaceship falling from the sky towards Woking.

At their headquarters in the British Museum, Mycroft Holmes tasks the League with researching Mars and returning to Horsell to observe the alien's behaviour.

During their reconnaissance, Allan, Hyde and Nemo encounter a Tripod, an enormous three-legged war machine, and set off back to London to warn British Intelligence.

After Mina recovers from her attack, Mycroft sends her and Allan on a new mission: they travel to the South Downs to find a scientist who may be able to help stop the invasion.

While Mina and Allan are away, Captain Nemo and Mr Hyde patrol the Thames in the Nautilus and fend off the oncoming Tripods.

While investigating the South Downs countryside, Mina and Allan meet a man called Teddy Prendrick (the protagonist of H.G.

Joined by other talking animals, the bear takes them to the hideout of Dr Moreau, who has relocated to the countryside and continues to create human-animal hybrids (humorously, all of Dr Moreau's hybrids resemble anthropomorphic animal characters from children's fiction, including Puss in Boots, Mother Goose, and Mole, Rat, Badger and Toad from The Wind in the Willows).

The chief is The New Traveller's Almanac, serialised in the back of the six issues and collected in the volume, serving as a guide to the world of The League of Extraordinary Gentlemen, including numerous references to classic and modern fictional works, e.g. the City of Opar, and Laputa, narrated by the creators.

Other parts include a cover gallery, a playable "Game of Extraordinary Gentlemen", an impossible "Nemo's origami Nautilus", a cautionary fable to complaining fans, and "Campion Bond's moral maze".