The story, as I see it, is pretty basic so far, but here's how I see it: [spoiler]The Traveler has Light, ans uses it to fight the Darkness. But right now, it's catatonic, so as Guardians we have to protect it until it wakes back up to save us again. Meanwhile, a bunch of enemy races have come out of the Darkness to -blam!- and pillage our worlds, our cities, and our race. These enemies are nothing compared to the Darkness, but they're like the boarding parties in that one level of Halo 2: if they can get close to us and kill the Traveler, the Darkness can come in and destroy everything. With that in mind, there is the Exo lady, who is fighting in unknown battles with an unknown faction. She finds the player, a Guardian who has shown promise, and tells them to look into the Black Garden, a place only the Reef seems to know about (which makes sense, since the Reef is a neutral faction in this war, and thus does business with the Darkness). The player goes to the Reef to ask for information, but the Queen and her brother do not trust him/her, so they send them to Venus to kill a Gate Lord. This turns out to be useful to the player, though, as the eye of a Gate Lord is enough to get them into the Black Garden. Thus, the player is sent to Mars, where it seems like the Cabal are already looking into stopping the Vex. Eventually, the Player gets to the Black Garden and finds that there is indeed a dark power there trying to kill the Traveller. The player destroys this power, and proves themselves a capable Guardian. The Exo lady now trusts the player, and may call upon him/her in the future, but it is very apparent that this was only the first step to ending the war with the Darkness. [/spoiler] As a first chapter, it does a good job of introducing us to the various locations/factions in this world, and at least for me, it makes me eager to learn more. Which I think was the point.