Is (short for Isabett) Twite is the younger sister of Dido, every bit as spunky and compelling as her older sibling and with the same habit of attracting bizarre adventures.

The two unputdownable novels in which she is the heroine, "Is" and "Cold Shoulder Road", are published here in a wonderfully satisfying double volume.

Is, travelling north to find a lost cousin, discovers an underground kingdom where children work as slaves in horrifying conditions, under the rule of the sinister Gold Kingy.

A year or two on, with Simon Battersea now on the throne, her aunt Ruth Twite disappears from Cold Shoulder Road.

Is needs all her courage and resourcefulness as she encounters the vicious gang of Merrie Gentry and other alarming forces that are at work across the country.