The year is UC 0123, and humanity is spread out across several colonies and the earth. An age of peace is shattered as the Crossbone Vanguard stage an assault on the station Frontier IV - their goal is to create a new age of aristocracy called Cosmo Babylonia; their method is destroying the federation and part of the populace. Seabrook Arno, a resident of Frontier IV, finds himself forced into the resistance in order to protect his friends. Piloting the new Gundam F91 model, Seabrook must now fight against the Crossbone Vanguard, as well as his childhood friend Cecily Fairchild.
In a research outpost in Turkey, an ancient relic known as Noah’s Ark has been discovered, and ARCAM, the world’s most secret organization in charge of keeping world order, must protect the ark from the deranged forces of the US Machine Corps. Yu Ominae, ARCAM’S #1 Spriggan, is an elite secret operative with one mission: Stop the key to NOAH’S ARK from being used by Colonel Mac Dougall, a cybernetically enhanced child with psychokinetic powers. Noah will be your grave!
Both of these are sci-fi action films where a young teenaged boy is soon caught up in lots of pretty and well animated action sequences interspersed in a narrative that is basically incoherent and frequently quite stupid. Spriggan is by far the better animated of the two (though Gundam F91 is no slouch I assure you) though Spriggan is also the more idiotic, as F91's story sort of makes sense no matter how fitfully delivered. If you could overlook the flaws of one to enjoy a visually interesting sci-fi action entertainment time you can surely appreciate the other; while F91 is part of a larger Gundam saga it also stands completely independent of other works (and the many loose ends it has are never wrapped up in other Gundam anime for the curious).