Zinnie and her sisters live in the murky tunnels beneath Edinburgh's Old Town. They keep out of the way of the authorities and remain undetected. Until, that is, rumours of a ghost bring unwanted visitors into the caverns they call home.

Among them, a young Arthur Conan Doyle, keen to investigate, and MacDuff, the shady owner of Edinburgh's newest attraction, the House of Wonders. Caught up in a world of intrigue and adventure, Zinnie seeks answers. But how can she discover what secrets lie in the House of Wonders while also protecting the sisters she holds so dear? A thrilling historical adventure featuring mystery in the tunnels beneath Victorian Edinburgh, for fans of Robin Stevens, Katherine Woodfine and Jennifer Bell.