Welcome to London. A city of smoke and fog, filled with airships, steamcars and towers soaring into space...

Jack Mason was a circus acrobat before his parents died. Now an orphan, he's trapped inside Sunnyside Orphanage, the gloomiest place in London.

That's until the famous detective, Ignatius Doyle, employs him as his new assistant. And when Scarlet Bell seeks assistance to find her missing father, they're flung headlong into a baffling mystery spanning centuries.

What could the Mona Lisa, Leonardo da Vinci and a secret society have to do with Scarlet's missing father?

And how is Doyle's evil nemesis, Professor M, involved?

The future of the world is at stake...