Liquid Crystal. Department 57, #7

A Department 57 story. When Crystal shares a bed with Bryn and Kai, the passion they wake in each other is as incredible as it is inevitable.  An unseen, unsuspected enemy rises up to threaten Crystal's life, until mermen Bryn and Kai, rescue her from a nearly fatal plunge into the Thames. When Bryn and Kai show Crys the secrets of underwater loving, the passion they release steams up the water. But their enemy still chases them, and now Crys, Bryn and Kai are in mortal danger.
Even in a city as busy and modern as London, England, old enemies lurk and old secrets hide.