Holly Black

When Mallory and Jared attempt to rescue Simon from goblins, they use a magical stone which enables them to see things that are normally invisible

With goblins, trolls, and the house boggart all trying to get them, the Grace children turn to Great Aunt Lucinda for help

Eleven-year-old Nicholas Vargas only thinks his life has been turned upside down after his developer father remarries and moves his new wife and daughter into the soon-to-be completed Mangrove Hollow. But an "expedition" to a nearby lake turns up a little nixie with a giant problem--the huge, lumbering, fire-breathing variety --and it's up to Nick, his stepsister Laurie, and his big brother, Julian (plus a familiar face from the original Spiderwick...

As giants start waking up and destroying everything around their Florida neighborhood, Nick, Laurie, Jules, and Cindy work frantically to find a solution.