I saw her file it away: a good Catholic girl come to supervise her in her detention. Every girl in England now, under the circumstances, made sure to be a good Catholic girl. Except her, of course. And, if only she knew it, me.

Escorting 'nine days queen' Lady Jane Grey across the Tower of London from throne room into imprisonment is Elizabeth Tilney, who surprised even herself by volunteering for the job.

All Elizabeth knows is she's keen to be away from home; she could do with some breathing space. And anyway, it won't be for long: everyone knows Jane will go free as soon as the victorious new queen is crowned. Which is a good thing because the two sixteen-year-olds, cooped up together in a room in the Gentleman Gaoler's house, couldn't be less compatible.

Protestant Jane is an icily self-composed idealist, and catholic Elizabeth is...well, anything but. They are united though by their disdain for the 17-year-old to whom Jane has recently been married off: petulant, noisily aggrieved Guildford Dudley, held prisoner in a neighbouring tower and keen to pursue his perogative of a daily walk with his wife.

As Jane's captivity extends into the increasingly turbulent last months of 1553, the two girls learn to live with each other, but Elizabeth finds herself drawn into the difficult relationship between the newlyweds. And when, at the turn of the year, events take an unexpected and dangerous direction, her newfound loyalties are put to the test.