A winged courier finds herself enmeshed in a byzantine intrigue of terrorism, betrayal and romance as a terrible plot threatens to overturn Ondirium, from the peaks (where reside the exalted) to the depths (where reside the other, lower castes). It will take all her skill and wits to unravel the mysteries, with the help of a self-exiled exalted clockwright and a group of eccentric friends.

If she succeeds, all is well. But if she fails, Ondirium may fall in flames and ruin ...