Roots: The millennium bug. There are references to Nintendo, Computing magazine, ER, Highway Patrol, Volkswagen, Ford, BMW, Land Rovers, Edvard Munch's The Scream, and Mozart. The Doctor reads New Scientist and quotes Shakespeare.
The codeword used to launch Russia's nuclear missiles is "Pravda", probably a reference to occasional Doctor Who actor George Pravda.
Continuity: A small nuclear device powers Voracians' synthetic systems. They can transmit destruct signals to their own kind via relay satellites. Silver Bullet Solutions Inc is a front for a group of Voracians, lead by chairman and CEO Byron Cutter. They are marketing a "brilliant" Y2K solution, which is a mixture of hardware and software and which is actually designed to catastrophically fail at midnight on December 31st 1999. They are aware of Stabfield's recent failure with I2 and partly blame this on his refusal to see them as colleagues rather than rivals. They are attempting to recreate Voractyll from the surviving fragments of code, and can get ninety-three percent of it from the pen that Sarah gave to Harry at the end of System Shock. The Doctor persuades the Voracian-controlled Dave Hedges to resist his programming and insert the Millennium Bug into Voractyll's code, causing it to destroy both itself and the Voracians when it encounters a date.
The Doctor was eventually persuaded to sign the Official Secrets Act in his previous incarnation and now seems to regret it. The Doctor offers a bag of dolly mixtures to George, but insists that they are jelly babies. He carries a stub of pencil and a black felt tip pen in his pocket. He carries a stethoscope. He produces, and drinks, numerous bottles of ginger beer from his pockets. He dismantles the impregnable intruder alarm installed by MI5 at Harry's flat. Harry gives the Doctor a pair of bright blue socks with snowmen and snowflakes on them for Christmas; the Doctor returns the favour with a linen bag that laughs in response to loud noises. The Doctor uses the sonic screwdriver to generate a beam of intense heat to burn paint off a window frame. He produces a small black box with a button and a red light that he claims is capable of detecting electromagnetic field of the type Voracian technology uses [presumably the device he built in The Android Invasion] and he advises using it sparingly in the presence of humans, as it emits a subsonic ganglia quotient field; he admits to Harry that in fact it is just a box with a bulb that lights up when the switch is pressed.
Harry's full name is, not surprisingly, Harold Sullivan. He is still working for MI5 in 1999. He drinks a pint of beer when meeting George. He prefers white coffee. When investigating Silver Bullet he claims to be working for "TARDIS Time Systems". Harry employs a young woman named Sylvia Webb to do his cleaning and ironing; she is injured when the Voracians' blow up his flat after retrieving the pen and taken hostage by the Voracian, who convert her into one of them, forcing Harry to shoot her. Harry makes an effort to keep his personal and professional lives separate; however, colleague Robert Gibson is the closest thing he has to a friend. Voracian Andi Cave rips a chunk of flesh out his neck.
By 1998, Sarah's Aunt Lavinia has died; Sarah goes off to Morton Harewood to sort out the house (K9 and Company). She gives Harry the I2 pen that she kept as a souvenir after the events of System Shock. She has an article on the Millennium Bug published in the January 1999 issue of Popular Technology.
Melsham's gas is a practically undetectable neural inhibitor that shouldn't be found on twentieth century Earth.
Links: This story takes place between The Deadly Assassin and The Face of Evil and is a direct sequel to System Shock. There is a reference to Ashley Chapel (Millennial Rites). The Doctor makes an allusion to the Celestial Intervention Agency (The Deadly Assassin).
Location: London, 1998; and Siberia, and London and Buckinghamshire, England, December 1999.
Future History: Terry Brooks is the Prime Minster of Britain in 1999; Phil Cotton is the Deputy Prime Minister. The Doctor orchestrates a military coup with the aid of General Randall to overthrow the Voracian-controlled government, including the manipulated human Brooks. The Voracians assassinate Defence Secretary Jennifer Hamilton in an attempt to frame the Doctor and Harry. A man named Derring is the US President.
Partly due to the Voracians' interference, the Millennium Bug causes loss of power and telecommunications in Malaysia, the traffic system in Hong Kong to fail, and power loss in Auckland. There is widespread power loss and chaos in Britain.
The Bottom Line: Written at a time when the Millennium Bug preoccupied the press and was a serious source of anxiety to many, Millennium Shock now seems horribly dated. The team of the Fourth Doctor and an ageing Harry Sullivan works well, but as a sequel to System Shock the novel suffers from the law of diminishing returns. Interesting to note however that several years before Aliens of London/World War III Millennium Shock features aliens disguised as humans in Downing Street, leading to a change in Prime Minister.