Who said that there were no pilots in the Middle Ages? What if in one of these romantic worlds a phase transition suddenly occurs and the work of a powerful disintegrator is noted, threatening the world with catastrophe? Extra-class chronoagent Andrei Korshunov, a former ace, a participant in the air battles of the Great Patriotic War, goes there, although not on a Yak, but with a sword in his hand, to restore order. With confidence in victory and... without hope of rest. After all, after this “business trip” there will definitely be a next one, followed by another one, somewhere to a “hot spot” in the future or present, where the breakthrough of the Black Vector of Counteraction, a strong and cruel enemy who intends to capture thousands of parallel phase-worlds, has been recorded, distorting their history and turning the inhabitants into obedient executors of their evil will.