The Cogheart Adventures Books in Order

The Cogheart Adventures are big, brisk middle grade adventures set in a steampunk version of the Victorian world. Airships cross the sky, wealthy households can afford clockwork servants, and mechanical animals are every bit as memorable as the humans. The books mix mystery, action, and feeling in a way that makes the world fun to visit, but never fully safe.

At the center of the series are Lily Hartman, the headstrong daughter of inventors, Robert, a thoughtful clockmaker's son, and Malkin, their sharp-tongued mechanical fox. Lily is brave and impulsive. Robert is careful, practical, and good at noticing details. Malkin is vain, funny, and often the first to complain, which only makes him more lovable.

The first book, Cogheart, starts with Lily's father missing after an airship attack and dangerous men closing in around her. That gives the whole series its shape. These are stories about children who are pushed into adult conspiracies and have to solve them themselves, usually while running, hiding, decoding clues, or scrambling aboard some improbable machine at the last second.

And yes, Malkin nearly steals every scene he walks into.

What makes the series more than a string of chases is that the mysteries are personal. Lily and Robert are not just hunting objects or villains. They are trying to understand their families, their pasts, and the strange world they live in. Lily has to reckon with her own difference after surviving with a mechanical heart, while Robert spends much of the series searching for truth about the people who shaped his life. Those questions give Moonlocket and Skycircus especially strong emotional stakes.

The setting keeps expanding as the books go on. There are smoky streets, clock shops, and gloomy corners of London, but also circus tents, airships, grand houses, and finally the bustle of New York in Shadowsea. Bunzl uses all of that to keep the pace up, while also building a world where invention can feel thrilling one minute and threatening the next. The villains tend to be theatrical, clever, and properly menacing, which suits the old-fashioned adventure mood.

These books move fast.

But they are not empty spectacle. Across Cogheart, Moonlocket, Skycircus, and Shadowsea, the series keeps returning to friendship, found family, prejudice, grief, and courage. If you like stories where smart children outthink dangerous adults, where the machines have personality, and where the heart of the story matters as much as the mechanics, this is what to expect from The Cogheart Adventures.