This book covers all three Mengsk's and their situations in one hit… Angus, Acturus and Valerian.
For any fan of the Starcraft series, this is a must read as it provides a lot of extra information as to why the Mengsk family is as it is, and how they have grown to be such an influencing power in the galaxy which you don't get in the games themselves.
Ties in very well with the games as you would expect, and after reading this and Heaven's Devils I promptly re-did the Starcraft 2 campaign again.