Faery in Shadow is a sequel to Cherryh's novella "The Brothers", which was first published in her 1986 collection of short fiction, Visible Light, and is based in part on Celtic mythology,[1] featuring such creatures as the fay race of the Sídhe, including pooka.

C. J. Cherryh's Faery is an alternate plane of existence where the Sidhe live, separate from, but still connected to, the mortal realm of humans.

The Sidhe are generally free to "step" in and out of Faery at will, but only a select few mortals have that privilege (or misfortune), and then normally under the control of a fay.

Caith mac Sliabhin, condemned by the Sidhe in "The Brothers" for committing patricide, wanders along the river Guagach, accompanied and tormented by Dubhain, a mischievous pooka.

Unbeknown to Caith, the birth of the twins 21 years ago set in motion a sequence of events that damned Gleann Fiain and cast a shadow over Faery.

From that day onwards, grief and misery struck the family, and mac Ceannann and Fianna were forced to vacate Dun Glas and flee with the twins to an abandoned hilltop fortress.

He draws Dubhain back to his cell, who in turn calls Nuallan from Faery, the bright Sidhe controlling their destinies.

There they make a fire with the remains of a staircase, but a ghost appears out of the smoke that transports Caith back to the night of the fall of the fortress and into the body of Padraic, head of mac Ceannann's household.

Firinne retrieves one of the burning timbers from the fire as a keepsake, and the twins set off for the sea to search for their selkie father, with Caith and Dubhain in pursuit.

Moragacht, furious at the loss of the Sidhe, prepares to deal with Caith, but he throws the charred piece of wood Firinne gave him into the fireplace which releases Padraic, the ghost from the hilltop fortress.

But Moragacht the witch defies the Sidhe by waking the ancient earth gods and practising stone magic, which disturbs Faery and its delicate balances.

Moragacht draws her magic from the earth powers, the banished gods, but her real desire is to control Faery, and Nuallan is her gift in exchange for this sorcery.

Moragacht wears Nuallan down with her dark magic, but Caith and Dubhain rescue him, each for their own reasons and in spite of the grief he has caused them.

[3] Then a lightning strike at Cherryh's house corrupted the original copy of the draft on her computer, and before she had a chance to rebuild the damaged file, Del Rey decided to take the book to print.

[3] While she left the plot and characters of Faery in Shadow unchanged, Cherryh rewrote large sections of the prose and infused Caith and Dubhain's speech with a Celtic dialect.