Tom Clancy's Net Force: Breaking Point by Tom Clancy, Steve Pieczenik

It is 2011 and in the peaceful retirement village of Daru on the Chinese mainland, local police find themselves helpless when the elderly residents suddenly turn violently insane. Tests on the food and water reveal nothing and the Chinese government - along with the rest of the world - are left to ponder on the implications of this bizarre group-psychotic episode. It is only when Net Force discover a top secret defence project has been compromised that the horrifying truth begins to emerge, and unless they can track down the traitor in time, a potentially devastating new super-weapon could be let loose.