Dorothy has vanished and all the equipment belonging to
Dot Chan has also disappeared, along with everything in the company's bank account.
Tom and
Ali are reduced to sharing a festering bedsit while they try to work out what has happened. Their first port of call is a convention of
Vavasorologists in an upstairs room at
The Dog and Fishbone. Here, Ali makes the acquaintance of
Patrice while Tom goes chasing after
Benjamin Unsworth. However, while Tom isn't looking, Benjamin is poisoned by an unknown agent and rendered unconscious.
In order not to get in the way of Ali's burgeoning relationship with Patrice, Tom goes to stay with his father, who it turns out has just fallen victim to a cryptocurrency scam. Tom decides to try to sort this out and arranges to meet with Matt Blank, a friend of a friend who is into crypto PR, who gives him a pass to the forthcoming launch of the Tulpencoin Super Plus ICO. In the meantime, he goes to the library to use the computer to try to find out where Benjamin is, which turns out to be St Jude's Hospital. He is also alarmed to receive a series of opaque messages from the deceased Rufus Fairbanks via his LinkedIn account, but he puts this to one side and instead concocts a plan to get into St Jude's. Meanwhile, Ali has brought home Bertrand, Patrice's ball python, to look after.
At St Jude's he meets Helen Matheson, who is in the process of removing Benjamin. He helps her carry him out, but they come under attack. Matheson shoots their attacker and they escape in a taxi, although she then chloroforms him and dumps him in the middle of the Kent countryside. Following an unexpected encounter with a Shetland pony and his owner, Tom makes his way back to London in time for his afternoon computer slot at the library, where he receives some more cryptic emails from Fairbanks. He goes back home and is so tired, he manages to accidentally free Bertrand, who immediately disappears under the floorboards.
The next day, Tom goes back to the library and receives another cryptic email and finally realises that whoever is behind the account is sending him a Fibonacci sequence. In the evening, he goes to the Tulpencoin launch at the Old Rococo Theatre, where he hears Kevin Wilberts and Tiger de Montfort speak. He goes backstage and sees a mysterious stranger ordering the killing of Matt Blank in the presence of both Wilberts and de Montfort. He escapes after being chased through the backstage area by Gunther and Dirk. The Old Rococo Theatre burns to the ground that night.
Tom and Ali wonder if the Fibonacci stuff is an attempt to lead them towards something on an old hard drive from Tom's laptop, which was sold in part-exchange for a new one. They go to Mad Mickey's Hardware Exchange to retrieve it, but find Mad Mickey dead. Eventually they manage to get the drive from Mad Mickey's lock-up garage and take it back to the flat, while Ali negotiates with Patrice on the use of her computer to find out what's on the drive. On the way to Patrice's the next day, Tom is held up by a gunman who is after the drive. He steals the bag, only to find out that Bertrand the python has snuck in there as well. In his panic, he manages to shoot himself, allowing Tom to escape.
At Patrice's, it turns out that the reason that Dot Chan was broken into was actually to steal Tom's laptop, which should have had something important on it. However, because the drive was swapped out, it's now on the one retrieved from Mad Mickey's. Ali connects it up to Patrice's machine and it turns out that the drive contains Rufus Fairbanks's crypto wallet, almost certainly copied by Dorothy on the night Rufus died. It also contains a virus planted there by the Tulpencoin people that connects to a server in order to allow them to steal any crypto they find there. It turns out that the server is located of the coast of Burnham-on-Sea, on an artificial structure known as Channellia. Tom recognises the owner of Channellia, The Hon Sholto Chelford-Bickerton, also known as the Seigneur, as the man who ordered the killing of Matt Blank.
Tom resolves to smuggle himself onto Channellia. He notes that their cover story is a venue for stag weekends, so he goes to Bristol and infiltrates the Todger Squad as they prepare to embark. He is surprised to encounter Dorothy, who has also smuggled herself on board, disguised as a croupier. She worked out what had happened early on and has been gathering information ever since. It turns out that the Seigneur and his motley crew have been stealing crypto and laundering it into hard cash via drugs bought on the dark web. Together, Tom and Dorothy engineer a distraction in the form of a fight amongst the members of the Todger Squad, and use this as a cover to get into the Channellia control room and set it in motion, so that they can sneak into the Seigneur's quarters amid all the chaos. Unfortunately they get captured instead and brought to the Seigneur's quarters anyway.
Just as they are about to be killed, however, the rig finally starts moving and it turns out that Tom has accidentally programmed it on a wild Fibonacci spiral. While this is going on, Tom and Dorothy manage to grab hold of the latest tranche of cash and make their escape from the rig by boat, just before it disappears over the continental shelf and sinks. The Todger Squad also manage to escape, but Gunther and Dirk are lost at sea. The fate of the remainder of the Seigneur's mob remains uncertain, although Tom and Dorothy think they glimpse the Seigneur himself just before the rig goes over the edge.
Tom and Dorothy get back to the shore at Burnham-on-Sea and get on the next train back to Bristol. However, on the way, Tom gets a call from Matheson who requests that they stop off on the way so they can meet in a beach hut in Weston-super-Mare. She pulls a gun on them and they give her the bag full of cash, but unbeknownst to her, Dorothy has swapped most of the money out for Tom's Todger Squad rugby shirt, now filled with sand to weigh it down. Tom and Dorothy make good their second escape of the day and return home. Tom uses some of the money to extricate his father from the Tulpencoin scam and Dorothy buys a load of new equipment to try to placate Ali.
