Tom Clancy's Splinter Cell: Fallout continues the novelization of Sam Fisher. In this fourth outing, Sam seeks vengeance after his brother's death all the while trying to stop terrorist from wiping out New York City with Plutonium Hydride-19. A radical Islamic leader who dreams of the past will do anything in his power to ensure that the future is destroyed-by hitting the technological world where it hurts: oil.
The plot begins in 2008, with Sam Fisher undergoing unfamiliar spy techniques training in the streets of San Francisco in a joint exercise between the Central Intelligence Agency and Third Echelon known as CROSSCUT. Fisher is soon after summoned to Maryland by Colonel Irving Lambert. Turns out, Sam's estranged brother, Peter, has been found barely alive off the coast of Greenland. Sam is told that Peter has developed a strange disease and has few days to live. It is soon revealed that Sam's brother died of poisoning caused by Plutonium hydride-19, or PuH-19. This deadly powder is 1,000x finer than flour and is capable of wiping out New York's entire population with just a cup's worth of the chemical.
Although driven at first solely by vengeance, Sam soon realizes that Peter's death should be the least of his worries as a network of Kyrgyz Islamic fundamentalists have toppled the moderate government of Kyrgyztan and, with the help of the North Korean government, have devised the ultimate antidote against the pervasive influence of the West and its technology: they will try to mutate a species of petroleum-eating Chytridiomycota fungus into a strain capable of making the whole world's oil supply disappear, a threat Fisher and Lambert continually refer to as Manas, in reference to the Kyrgyz epic poem. In order to do this, the terrorists snatch some of the world's leading scientists and force them to cooperate. Sam gets his final lead by tracking one of the abducted scientists in a search that will lead him to a place such as the streets of Montreal, Quebec, Canada, an isolated Kyrgyz community in Cape Breton Island, the Great Rift Valley in Kenya, Pyongyang, North Korea and a Kyrgyz complex hidden in the Tian Shan mountain range.
Fallout takes place more or less before the events of Double Agent. Fallout is largely a stand alone story with no connection to any previous book in the series, although there are a few references to a few locations, characters & items introduced in Checkmate. Conviction (novel) and Endgame follow up on details established in the previous two books, with extra details from Double Agent. There are no direct references to Splinter Cell (novel) and Operation Barracuda.
Fallout takes place in spring 2008 (in the northern hemisphere). This would make it chronologically after the Iceland mission (September 2007 in version 1/January 2008 in version 2), but before JBA infiltration in Double Agent (Version 2). In Conviction, Sarah Fisher's death/Iceland follows the Essentials/Version 2 date of 2008, moving the JBA incident closer to winter 2008 (Version 1 occurs in March, which is early spring, placing it concurrently with Fallout), as Sam spends about half of the year in Ellsworth Federal Penitentiary. Conviction (game) adopted a combination of the version 2 timeline (I.E. date of Sarah's death), with details from version 1 (Sam shooting Lambert in New York City). As such there is no consistent timeline between the two (and other sources). Therefore it is unclear how these details affect the timeline and how the novel fits into them.
The next two books, Conviction and Endgame, make a few offhand references to this book mainly some of Grim's past, and layout of NSA headquarters, and Fisher's Sykes dagger, among other things. They also make references to Sarah's and Lambert's death in Double Agent (but also seem to have an unclear timeline sharing elements of both versions of the games). Fallout, and the latter two books seems to fit closer to the Version 2 timeline which places events of Double Agent closer to late winter 2008 (with Fallout occurring spring of 2008)
The Tom Clancy's Splinter Cell: Conviction Starter Kit makes references to locations Sam visited during this novel. The novels are stated to be part of the complete history of Sam Fisher.