Taya investigates the source of terrorist threats to her city, in the process falling in love with a crusty, eccentric clock-maker and discovering corruption in the government. Taya is an Icarus, a person who uses metal wings powered by an ore called Ondium to fly and run errands for citizens of the city of Ondinium. She dreams of one day being promoted to work in the diplomatic corps of Icarii who get to travel to places other than Ondium. Since Taya is an Icarus, she's one of the rare citizens of Ondinium who are allowed to interact with members of all castes,as usually communication and living quarters are strictly segregated. Ondinium's caste system features a group of nobles called the "decaturs" and the "exalteds" at the top of the hierarchy, the latter often found wearing beautiful robes and covering their faces with masks.
One day, as Taya was flying by on an errand, she saves the passengers traveling on a wire-ferry (essentially a cable car of some sort) from plummeting to their doom. Apparently there have been terrorist attacks on the high-ranking members of Ondinium lately. Taya is recruited by an exalted named Alistair to watch for suspicious activity in Ondinium. Alistair is charming and handsome and seems to like Taya, despite their disparity in caste. He also happens to be a member of the governing council of Ondinium.
Later on, as she is returning home, Taya is mugged and her wings almost stolen by Alzanans, who are foreigners in Ondinium. She is rescued by an eccentric decatur, Christof, who is Alistair's “outcast” brother. Christof is an exalted, however he has rejected his own caste and seems to be against the entire caste-system altogether, an unusual thought for a high-ranking citizen of Ondinium to harbor. Christof owns a small clockwork repair shop and is able to fix Taya's broken wings. Later that night, as Taya is about to leave, there is an explosion nearby. Christof tells Taya to return to her eyrie (the place where Icarii live) while he goes to investigate. Taya thinks Christof didn't seem too concerned about the explosion and she suspects he might be involved in the terrorism since he has radical ideas about the caste system.
Taya decides to interrogate Christof further. Taya discovers that Christof is crusty and hostile on the outside but a caring and compassionate person on the inside. Christof puzzles Taya, however, as he is awkward and prone to scowling and she doesn't know whether she can believe that he is not involved in the dissident terrorist activities. Later, Taya has dinner with Christof's brother, Alistair, who shows that he is interested in her. She contemplates whether she should continue flirting with Alistair, as her association with him might be useful in future promotions as an Icarus. As she gets to know Alistair more, she gets invited to more upper-class events with him. Alistair tells Taya that he has created a program for the great engine at the center of Ondinium. The program is called the Clockwork Heart, and can calculate the likelihood two people are to be a good match in marriage based on questionnaires and socioeconomic status. He explains that certain citizens hate the idea of machines running Ondinium and these groups might be responsible for the terrorist acts against engineers, lately. Taya tells Alistair that she suspects Christof might be part of a group of dissidents called the Torn Cards and Alistair tells her it is unlikely but that she should stay away from him in case her suspicions prove right.
Taya can't help but continue investigating Christof, however. She sneaks into his Clockwork repair shop and sees that he has books about how to make bombs. Christof confronts her but before they can get into any arguments, another bomb explodes. Taya rushes to the scene and learns that Alistair might have been a victim in the bombing as a body was found bearing a clock that Christof made for him. She calls the lictors (essentially the policemen of Ondium) to arrest Christof because he's likely involved in the bombings. To her great surprise, Christof accuses her to be a terrorist, too. Both of them are arrested but since there isn't enough evidence to incriminate them, they are both allowed to go. Christof and Taya apologize to each other. Taya learns from Christof that Alistair had been going to work on the Clockwork Heart that day. Apparently, Christof and Alistair's childhood was full of suffering because they watched helplessly as their father beat their mother and the other exalteds pretended nothing was happening. This was one of the reasons why Christof exiled himself from his caste and also why Alistair created the Clockwork Heart – to prevent violent marriages such as those his mother went through.
Taya and Christof visit Alistair's programming lab and meet his programmers. They are holding vigil for the likely death of Alistair and they were planning on running their first version of the Clockwork Heart program that night. Taya and Christof learn that Alistair was also involved in creating the codes for the Loyalty test – a test that all citizens of Ondinium have to take to minimize the risk of citizens becoming dissidents. They learn that there might have been something fishy going on with Alistair and his partners. Christof suspects that one of his partners may have wanted to use Alistair's knowledge of the Loyalty test to circumvent the system and then killed Alistair because he was found out. Alistair's subordinates tell them that they think Alistair himself may have been writing something more than just a matchmaking program.
Taya and Christof sneak into the Great Engine to retrieve a copy of Alistair's Clockwork Heart program so that they can investigate the issue further. The Great Engine is inaccessible by ground because it has been sealed off, however, thanks to Taya getting wings for herself and Christof, the two are able to access the Great Engine by flying into it from a central shaft. They find that there is someone there with them, as he or she has left tracks on the dusty floor of the Engine tower. They discover the person following them is none other than Alistair, who has feigned his own death. Alistair reveals that the Clockwork Heart program was actually meant to circumvent the security program of the great engine so that Alistair could re-program the great engine to his own ends. He tries to convince Taya that he's only got the best intentions in mind, but Taya is horrified as she sees that Alistair is mad and wants to control every aspect of Ondinium society. Taya and Christof have an altercation with Alistair and end up subduing him until the lictors get to them.
Alistair is sentenced to execution. Christof talks to the city council and arranges to lessen his brother's sentence to that of exile, instead. The story ends with Taya and Christof arresting the other culprits in the terrorist attacks. By this time, Taya and Christof find out they like each other and begin to have a tentative relationship.
Best part of story, including ending:
I thought the idea of a great engine running programs to control all aspects of a society was very intriguing/unique and an interesting basis for this steampunk-ish fantasy.
Best scene in story:
My favorite scene was when Taya teaches Christof how to use the Icarus wings. It was a rare scene where Taya and Christof just enjoyed being together and Christof wasn't his usual cranky and crusty self.
Opinion about the main character:
I like that Taya saw Christof's gentle side even though he tried to hide behind a defensive wall of rudeness. Despite so many awkward situations, Taya was patient and even amused by Christof and his antics. I think it was her patience and open-mindedness that won Christof's trust and love.