REAMDE, by Neal Stephenson
This book is great and you should read it immediately.
Quick Summary: A virus, created by Chinese hackers, is set loose inside an MMORPG called T’Rain; once encrypted, the virus encrypts the player’s hard drive and demands a ransom, which is to be paid in-game. The boyfriend of the niece of the game’s creator is a hacker who accidentally transfers the virus to his Russian Mafia contact while selling a batch of stolen credit card numbers. This pisses off a crazy Russian Mafia boss, who kidnaps the niece and the boyfriend and takes them to China to track down the writers of the virus.
Shit then gets real, but this is a spoiler-free summary.
The only thing I can almost complain about is that some of the details regarding T’Rain and the interactions with the game’s two primary worldbuilders (one a J.R.R. Tolkein-type Oxford professor who focuses on canon, the other a hack who cranks out several fantasy books a year) are completely extraneous and do nothing to advance the plot; however these sections are entertaining so I can give it a pass.
Rating: 5/5, would read again if it wasn’t so long.