The Hades Factor (Covert-One Book 1)

The very first Covert-One novel from the Sunday Times bestselling author Robert Ludlum.
An unknown doomsday virus has claimed the lives of four people - including the fiancée of Covert-One's Lt Col. Jon Smith. Devastated and enraged, Smith uncovers evidence that this was no accident; someone out there has the virus, and the pandemic that threatens millions of lives was planned...
Not knowing who to trust or where to turn, Smith assembles a private team to fight the deadly virus. As the death toll mounts, the quest leads them to the highest levels of power and the darkest corners of the earth. And Smith and his team must hunt down a genius determined to destroy them.