When the boiler explodes on the airship Lucky Lady, killing three men, first mate Gavin Roberts finds himself in the crosshairs of one of the most powerful men in Europe. Sir Cornelius Smothers, an iron-fisted shipping tycoon, has lost his youngest son in the boiler explosion and he holds Roberts responsible for the accident. Determined to rescue both the Lucky Lady and his own name, Roberts negotiates a deal with Smothers to purchase the ruined airship within three years, a bargain which promises certain death if he defaults. Renaming his crippled airship the Horizon, Roberts begins to rebuild her with the help of an eccentric inventor and a motley handful of loyal crew members. When the Horizon rises to life again as the fastest airship in the sky, she earns fame but also increases Smothers' wrath against her new captain. Battling airship pirates and dodging malfunctioning automatons, Roberts must fight to keep the Horizon in the air and pay off his debt before his luck and his time run out.