Battletech: Lethal Heritage

Battletech: Lethal Heritage - Michael A. Stackpole, Christopher Graybill This is where the Battletech novels moves from "The Original Series" to "The Next Generation".
The mysterious clans enter the Inner Sphere, and the families from the Great Houses give their children a degree of responsibility.
Victor Steiner Davion and Kai Allard Liao have graduated from their respective military academies and get a taste of action and command.

The real feeling in this book is how no-one knows what they're up against. Superior mechs, battle armour, and an implacable foe which has never been seen before, with ComStar plotting behind the scenes to keep their place.

Great characterization and lots of action.