Switcher Tess is about to discover her dark sideTess is a Switcher, able to change into any creature at will.

She believes she has experienced everything her powers have to offeruntil she meets Martin, another Switcher, who seems to have a mysterious power over the Dublin rats.

Martin has found a use for his gift that Tess could never have imagined.

It is dangerous and terrifying, but also exciting, and Tess can't resist the temptation to explore Martin's dark and thrilling world.

Will she find the strength to resist, or will she be pulled permanently into darkness?