Sixty years ago, the angels of Io disappeared. They had walked the city openly for as long as anyone could remember. Then, gradually, they were simply gone. No announcement, no explanation. Since the angels disappeared, magic has been acting strangely - not quite doing what it's supposed to, or having unexpected side effects. Most magic users have limited or completely stopped their use, though there are some who still practice it despite the risks.
The angels left behind Firstlight - a golden liquid that ran in angelic blood and is now channeled into Engines, devices that power the entire city. Descendants carry traces of it in their own blood, a fraction of what the angels once had, a pale shadow of the power their ancestors once wielded.
Engines aren't limitless. When worked too hard, or too old, they begin to fail - smoke leaking from their exhaust ports as a warning sign they're burning out. Once fully spent, an Engine is stripped of its abilities and discarded. Desperate hands sometimes repair and repurpose these burnt husks into something rougher and more dangerous, known as Burners.
Io itself is built in three tiers, bordering a large rift known as the Chasm, where burned out technology and unwanted waste is dumped. At the top sits Aurum, a walled paradise of golden spires reached only through Eden Gate, heavily guarded and rarely opened to outsiders. The Council - the most powerful descendants left in Io - rules from the Crown, the tower at Aurum's heart, with Gabriel Arden, the Governor, holding the loudest voice among them. Elsewhere in Aurum, the wealthy spend their lives between Lumen Row's salons and theatres, the cultivated housing estates of Orchard Hill, and the quiet monuments of Seraph's Rest, where the city's history and the angels who built it are remembered.
Below is the Waterways, where most of Io actually lives - a sprawling district named for the channels that carry Aurum's water and waste down from above. Conditions only worsen the further the water travels: Ratbridge festers with disease and vermin, Cutthroat Alley earns its name from the criminals that linger there, Smogchoke can't breathe past the haze of burned-out Engines, and Toxfield is drowned in acid rain.
And further down still lies the Undercity: the first thing the angels ever built, ancient and abandoned - now just ruins, silence, and whatever waits in the dark. Only the desperate go. Few return, and none come back unchanged.
Whatever your reasons, you were all in Angelica Street Station in the Waterways when two private investigators were murdered, and when the dust settled, the evidence pointed to you. Now you're fugitives in your own city, and the only way to clear your names - and maybe uncover something much larger than yourselves - is to find out what really happened.
A few days before everything fell apart, each of you received a letter in pristine handwriting with no explanation. "If you ever find yourself in trouble, go to Mire & Marrow Antiques in Ratbridge. You have a friend there. - LL"
At the time, it seemed like nothing. Now it's the only lead you have.