Astrid Bailey is content living alone, balancing her career as a contract machinist with her true passion: making 'felicitation devices' for her discerning female clients.
At the upcoming World's Fair, with its substantial cash prize, there's an opportunity for her to open the shop she's always imagined and solve her financial woes. With questionable credentials, though, she's unable to enter without a reputable businessman to vouch for her.
Eli Rutledge, noted watchmaker, needs to enter the World's Fair to maintain his reputation as an innovator, but he's fresh out of ideas. With no other options, he agrees to Astrid's proposal, lending his good name to her scandalous invention. When construction heats up, so does their chemistry - and the complications. Astrid is unaccustomed to accepting help, especially from a privileged businessman like Eli, even if she can't keep her hands off him. Eli is losing his fight to an attraction that could spell professional disaster and heartbreak.
As the Fair date approaches, Astrid and Eli must decide how far they'll go for the business...and for each other. 
Combustion contains steamy f/f m/f encounters and gratuitous liberties in an alternative-history steampunk London (all in the quest for happily ever after).