The story was really fragmented. It normally should be told sequentially, but this was not clear from the missions that opened up. The side stories confused it by a lot. I'm not sure if there was a key but they could have differentiated it by stating that it was a side story to the main plot on the selection screen. From what I've managed to piece together here it is in [b]very simplistic terms [/b]and I'm a bit sketchy on the details. Story Summary [SPOILERS]: After the collapse, the traveller in its weakened state created ghosts to find guardians that could wield it's "light" power to fight back the darkness. The aim of the last city is to revive the traveller. Your ghost finds you and revives you with light, finds you a ship and gets you to the tower. You go back to the spot you found your ship to get the interplanetary hyperdrive for your ship. The fallen boss has it so you kill him to get it back. You discover that the hive are on earth and that the fallen are fighting them to get access to something. You find out in the warmind that the computer shows something somewhere is suppressing the traveller's light. You locate the array to pinpoint the rough location of the source, discovering it is on the moon. You go to the moon to find clues, going to an old moon base station and tracing the last known guardian's ghost to a certain location. You discover a hive base and inform the city of the events unfolding there. A strange exo hunter appears to watch over you. You delve deeper into the base to discover that fragments of the traveller are being used by the darkness to suppress its powers. Your ghost discovers there's a bigger suppressant somewhere on Venus. You go to the old academy for clues and discover the vex. The stranger gives you a hint about how to revive the traveller. There is something in the black garden it seems, but it is not known how to find it. Your paths are different but the traveller's revival will probably help her cause too. Her ship is being attacked by vex so she has to go off, but she suggests speaking to the Queen of the Reef. You go to the Reef to ask the Queen for help on finding it. She says she knows where it is but you have to get a vex gatelord's head as it has the access codes/memory fragments. You traverse venus trying to track where a vex gatelord could be and finally pinpoint a location. On the way you discover that the vex are guarding something called the vault of glass which holds many secrets, but the gatelord is more important so you kill it and bring it back to the queen. The queen's brother reluctantly tells you that the black garden is on mars in the exclusion zone. You owe them a favour when the time is right. You go to mars and fight through the cabal to pinpoint where in the exclusion zone is the way to the black garden. You eventually find an area guarded by vex and fight through to a portal where you are transported to the black garden. You discover a giant black heart which is the main reason why the traveller is dying. You destroy it and save the traveller. There is celebration in the city for your triumph, but you choose to ignore it. The stranger suggests that your paths will cross again and gives you a gift. The story arc ends, suggesting that you will now travel further to fight back the darkness. The side stories are actually interesting too but I need to play through them again to figure out what the heck is going on. Parts of the story are told by the ghost within the mission which you barely pay attention to since you are fighting off hoardes of enemies while the ghost is dycrypting/hacking computers. Hence why everyone is confused! I'll have to play through the story mission again with other characters to fully understand it properly, but hopefully the rough sketch above helps!