Rook endgames are fundamental to chess. And this book can be read by a complete beginner. All one needs to know is the rules and how to checkmate with King and rook against a lone King.
The author does get off to a bad start with his first (and worst) diagram (how did those Kings get there?). But the rest of the book is excellent. The only improvement I might make would be to include a little on endgames with two rooks on each side.
Ward begins with some absolute basics. Rooks belong behind passed pawns! Checks from the side sometimes salvage draws. Shoulder off that enemy King! Push passed pawns! Keep your rook away from the enemy King. Cut off the enemy King.
We learn about the Opposition. And we learn the most important thing about rook endgames: rooks need to be active. You put them on open files. And on the seventh rank. And you consider sacrificing a pawn to activate your rook.
We learn that when you have a pawn on the seventh and a rook defending it on the eighth, the "skewer" trick is often the way to win.
We see examples of King and rook versus pawns. And we discover that when the defending King is far away, two connected pawns on the sixth defeat the rook.
Ward then teaches us to defend with King and rook versus King, rook and pawn. These positions are drawn unless the defender has a bad King position or an inactive rook. When we have the better King position and the pawn, we learn how to reach the Lucena position and win. And we learn some more tricks, such as stalemate threats and underpromotion.
We also are shown endgames where each side has several pawns. Of course, a basic aspect of rook endgames is that a pawn advantage is often not enough to win, while that same advantage tends to win with the rooks off the board. The defender almost never wants to swap rooks! When considering a rook swap, we're reminded to be really sure about the ensuing pawn endgame.
We see why an extra pawn, with all pawns on the same side of the board, is usually a draw. And we are shown that a 3 to 1 advantage on one side of the board and a 2 to 1 disadvantage on the other side is much better than a 3 to 2 advantage on one side and 1 to 1 on the other.
I liked the fact that we are shown a little about how to defend with King and rook against a King, rook, and two isolated pawns (a and h files or a and c files). That's important, albeit somewhat tricky.
Ward finishes with some practical examples from his games. At the end, there is an easy quiz with twenty multiple choice questions (and detailed answers).
I recommend this book. It is a good introduction to the subject.