the last mission of Heroes of Might and Magic V and its continuation.

In the original game, Isabel with red eyes appeared after completing the 5th mission of the 6th campaign (the last one, overall). Then, according to the plot, "Hammers of Fate" and "Tribes of the East" follow. Dark Messiah is at the very end. In general, if you want to experience the entire story and the delights of necromancy from versions 1.0 to 1.3, buy the game "in parts" rather than the "Gold Edition".