When Grace balks at taking yet another life to ensure her own survival, she accidently loses the necklace storing the last of her magical lifeforce. Suddenly desperate for the lifeforce she failed to steal and with nothing held in reserve, she must recover her necklace before sunset or drown another victim. If she doesn't, she'll die, and she only has minutes left. Determined not to kill until she has to, Grace makes a regrettably hasty promise to regain her necklace, not realising the promise will expose a secret other magical Creatures would kill for. The secret? Mermaids are the only magical Creatures who can store excess lifeforce for later use, an ability her kind would be enslaved for of other Creatures found out. With her life and those of her sisters at stake, Grace is forced into a desperate fight to save her kind from the malign intentions of a succubus and her cohort of ghouls, all determined to do whatever it takes to control her ability. If she fails, mermaids will face a war they cannot win.