Set 25 years after the first game, Dungeon Hunter 2 has a wonderfully transparent and simple plot. Even the Gameloft product sheet keeps it as basic as can be: "You are one of the immortal king’s sons. Survive a war, escape from prison, and travel across your realm to save everything!" That's it.
To be honest, that's all you need, because the fun with DH2 is in the exploration. And even more so in multiplayer.