London, 1876. Hetty Feather is just a tiny baby when her mother leaves her at the Foundling Hospital. The Hospital cares for abandoned children - but Hetty must first live with a foster family until she is big enough to go to school.

Life in the countryside is sometimes hard, but with her foster brothers, Jem and Gideon, Hetty helps in the fields and plays vivid imaginary games. Together they sneak off to visit the travelling circus, and Hetty is mesmerised by the show - especially the stunning Madame Adeline and her performing horses.

But Hetty's happiness is threatened once more when she must return to the Foundling Hospital to begin her education. The new life of awful uniforms and terrible food is a struggle for her, and she desperately misses her beloved Jem. But now she has the chance to find her real mother. Could she really be the wonderful Madame Adeline? Or will Hetty find the truth is even more surprising?