From the website:
Ancient skeletons and mouldering corpses crawl from their barrows, called forth by the dark sorcery of Nagash, Supreme Lord of the Undead. Ancient beyond reckoning, cruel and infinitely calculating, Nagash seeks to remake the Mortal Realms in his own image, transforming them into an ordered empire of mindless thralls, leashed to his will. In opposition, thunder rolls as the Stormcast Eternals, heavenly champions of order, rage forth to meet this threat head-on in epic clashes to decide the fate of the world, This is a new epoch, a time of mighty battles and unending war, a time of heroes and monsters. This is the Age of Sigmar!
A perfect introduction to Warhammer Age of Sigmar, and the wider hobby of collecting, building, painting and playing with Citadel miniatures, Tempest of Souls is a starter set packed with miniatures, rules and accessories that will have you up and running in no time. It includes 32 miniatures split across the factions of the heroic Stormcast Eternals and ghastly, undead Nighthaunt – mortal enemies locked in unending combat – along with detailed guides on assembling, painting and playing with them.