I haven't read it myself, but Zero Day by Mark Russinovich should be a very good book and realistic as well.
From the official website of the book:
An airliner falls from the sky. A nuclear reactor nearly melts down. An oil tanker runs aground. Jeff Aiken and Daryl Haugen believe these incidents are the result of a massive cyber attack that's under way. The clock is ticking as they race to figure out who is behind it and how to stop it.
Written by a global authority on cyber security, Zero Day presents a chilling “what if” scenario that, in a world completely reliant on technology, is more than possible today—it’s a cataclysmic disaster just waiting to happen.
More about Mark (from his blog) to show that he knows what he's writing about:
Mark Russinovich is a Technical Fellow in Windows Azure, Microsoft's cloud operating system group. Russinovich is a widely recognized expert in Windows operating system internals as well as operating system architecture and design.
Russinovich joined Microsoft when Microsoft acquired Winternals software, the company he cofounded in 1996 and where he worked as Chief Software Architect. He is also cofounder of Sysinternals.com, where he wrote and published dozens of popular Windows administration and diagnostic utilities including Autoruns, Process Explorer and Tcpview.
Russinovich coauthored "Windows Internals" and "The Sysinternals Administrator's Reference," both from Microsoft Press, authored the cyberthriller Zero Day, is a Contributing Editor for TechNet Magazine and Senior Contributing Editor for Windows IT Pro Magazine, and has written many articles on Windows internals. He has been a featured speaker at major industry conferences around the world, including Microsoft's TechEd, IT Forum, and Professional Developer's Conference, as well as Windows Connections, Windev, and TechMentor, and has taught Windows internals, troubleshooting and file system and device driver development to companies worldwide, including Microsoft, the CIA and the FBI. Russinovich earned his Ph.D. in computer engineering from Carnegie Mellon University.