It's free! It's on-line! It's 267 pages! It's .NET Book Zero: What the C or C++ Programmer Needs to Know about C# and the .NET Framework and you can download it here.
.NET Book Zero actually originated as Chapter Zero in Applications = Code + Markup, but I realized it would be a little long, so I spun it off into its own book, and then it got really long, and took me way too much time to get done. (And what's more — I don't think it's quite finished yet. It's missing chapters on DLLs, collections, reflection, and XML, which I'd like to add sometime in the future. But it has plenty of other information, and probably lots of typos as well because it hasn't been properly edited. But did I mention that it's free?)
If you've been coding in C# and .NET awhile, you don't need this book. But if you've just recently realized that you need to learn this stuff (or maybe you know somebody like that?), then this book may be ideal.
And then, after reading .NET Book Zero, maybe you might want to buy one of my other books. (Yes, the first taste is free.)