It could have been aliens, it could have been a trans-dimensional rift, nobody knows for sure. What's known is that there was an Event, the Rifts opened up, and everyone caught inside died.
Since then certain people have gone in... and returned, bearing priceless technology, almost magical in its advancement. When Ashe the Rat - the best Rifter of her generation - dies, the authorities offer her student Svinga a choice: go in and bring out the thing that killed her, or rot in jail.
