They finish their dinner early, not having enough cash to continue ordering at the restaurant they had chosen; on their way to a cheaper establishment, the younger of the two men declares his new religion of Evolution, and asks the other fellow to become his disciple.

The rest of the book finds Earl Lavender leading the way through London, assuring Lord Brumm that Evolution will care for them.

One mysterious Veiled Lady who pays their bill leads them, afterwards, to an underground city where they are all flogged with knotted cords as part of a strange religious ritual, and then given beds for the night.

Earl Lavender perceives that the Veiled Lady may be the fittest of women that he's been looking for, but he is kicked out of the underground city for declaring his passion for her (as these floggings are intended to be completely non-sexual) and Lord Brumm is soon ejected likewise; they are warned that they may return to the underground city in the future but that if there is any more misbehaving, they will be stripped and sent forth into the London streets during broad daylight.

Earl Lavender manages to break another rule, but the Veiled Lady and the overseer of this underworld make arrangements to spare him the usual punishment, and instead give him a stern talking-to.