The Arcane Society series is great fun, romantic suspense in an underworld of psychics. In this one, Grace and Luther meet in Hawaii to track down a psychic serial killer, and discover a dangerous drug is in common use by an organization of psychic criminals. Grace and Luther need an understanding family around them to deal with an odd criminal family, whom they have accidentally stirred up like hornets. La Sirene is an excellent invention -- as long as you can get rid of her once you've invented her.