'...come to London to take up a position on the London Times. He proves his usefulness by sending them new clients, which is fortuitous as Neptune is broke, having paid his entire fortune to Shadow as ransom for his sister and Shark. Their first case sees them initiated into a cult, hypnotizing and using the followers for the leader's enrichment.
'Unable to afford petrol for his car, Neptune borrows twenty pounds from Shark only to see his own initials on the note. NK in the right hand corner. Every note in the ransom bundle was similarly marked. Following the trail of the money leads them to Epsom racecourse and with the cooperation of the track's manager they eventually get a lead on the punter that paid out the marked money.
'This leads them to the hit and run driver who critically injured Neptune's brother-in-law, and eventually to the Shadow himself as they follow a trail that sends them to Paris, where Shark's dalliance with a couple of French ladies of easy virtue gives them a clue to the Shadow's true identity. The case comes to a head at the Shadow's 12th century chateau in Quercy, Bordeaux, where they risk life and limb to capture him in a climatic showdown of good versus evil.' (Publication summary)