It features the first true appearances of the remaining Tamers of the Tempest, including the unpossessed Lucas Caravaggio, Kim Topher, and Mark Cho. Rendell Locke, Ellie Whedon, and Erin Voss had all been featured previously.
The majority of the volume takes place in flashbacks, with only two scenes happening "now": one extended scene of Tyler and Kinsey Locke using the Timeshift Key to travel back to 1775 and then to 1988, and the final scene of the volume where the siblings return to their rooms after learning their father's history. There are also some near-present scenes set "four days ago", leading up to the discovery of the Timeshift Key.
The sprawling tale of the Locke family and their mastery of the 'whispering steel' thunders to new heights as the true history of the family is revealed to Tyler and Kinsey. Zack Wells assumes a new form, Tyler and Kinsey travel through time.
Tyler and Kinsey Locke have no idea that their now-deceased nemesis, Lucas "Dodge" Caravaggio, has taken over the body of their younger brother, Bode. With unrestricted access to Keyhouse, Dodge's ruthless quest to find the Omega Key and open the Black Door is almost complete. But Tyler and Kinsey have a dangerous key of their own — one that can unlock all the secrets of Keyhouse by opening a gateway to the past. The time has come for the Lockes to face theri own legacy and the darkness behind the Black Door. Because if they don't learn from their family history, they may be doomed to repeat it, and time is running out!
Colonel Adam Crais's minutemen are literally trapped between a rock and a hard place; in the first days of the Revolutionary War, they find themselves hiding beneath 120 feet of New England stone, with a full regiment of redcoats waiting for them in the daylight... and a door into hell in the cavern below. The black door is open, and it's up to a 16-year-old smith named Ben Locke to find a way to close it. The biggest mysteries of the Locke & Key series are resolved as Clockworks opens, not with a bang, but with the thunderous crash of English cannons.