Spell Spring. Earthaven, #2

Prepare to be enchanted in this long-awaited sequel to Spellfall. It has been six months since the rebel Caster Lord Hawk kidnapped Natalie in an attempt to bond her to his spellclave and was imprisoned inside the Thrallstone by his son Merlin. Natalie and her family have moved to Scotland, where her mother's magehound is teaching her magic, while Merlin stayed behind in Earthaven to help heal the root system of his father's poison.
Now the soultrees of Earthaven are preparing for the Blossoming, when treemages will fertilize the flowers with unicorn dust to grow new spells. But Earthaven's magic is draining away through the gateways into the human world, where Lord Hawk is reforming his spellclave. The Spell Lords summon Natalie to take her mother's seat on the Council of Oq, but one of the young treemages chosen to complete her spellclave has fled through the forbidden Thrallstone gate, where his loyalties are tested when he meets Lord Hawk.
With the Blossoming fast approaching, Natalie and her friends once again find themselves fighting Lord Hawk's Casters in a desperate race to gain Power of Thirteen - but this time Natalie has learned some magic and is determined to do things her way, no matter what the Spell Lords say... Praise for Spellfall:"Roberts knows exactly how to rack up the tension and create parallel universes." The Guardian.