The Ark has always been considered one of the theoretically-heaviest defenses in meeting the Ruy Lopez, though also the most exciting and definitely the most beautiful of all.  It requires tactical vision, good calculation and memory, but not just from us – from the White side too. Let’s not forget that! I also must say that no good lines are absent of theory, so if we’ve decided to learn something “finally”, I argue that it can very well be an ambitious, double-edged line too! :-) I should also mention that this book is a complete Black repertoire starting from 3. Bb5 a6, the exchange variation being the first chapter. The publisher and me agreed on offering a full package, one that should prove useful for many years to come!