In the City of Brass, a young girl named Theodora is working for an upper city aristocrat in order to support herself and her sick mother. One day, she stumbles upon an old music box owned by her employer, and she plays it. Doing this suddenly sends her back in time, where she finds an ancient city with the cleanest skies she has ever seen. After being recruited by Marcus, the local army general, she sets out to help him find a mysterious artifact called the Tempus Sundial. This relic is said to be able to reverse time, as well as all of it effects. However, the alliance between Theodora and Marcus begins to wear thin as the two realize they have very different ideas on how the relic should be used.

This music box, which Theodora found abandoned in her boss’ attic, is the device that ultimately sends her back in time.