Carole E. Barrowman & John Barrowman 
Book of Beasts [EPUB ebook] 

‘It won’t be long now. Death will come soon enough…’ Twelve-year-old twins Matt and Emily Calder may be divided by time, but they are united in their mission to close Hollow Earth before the monsters inside can destroy the world. The key to success lies with their dazzling Animare talents: they can draw things into life and travel in time through art. But there are monsters outside Hollow Earth as well, intent on taking control of the beasts for themselves. And their own father is the worst monster of all… Even when you travel in time, time has a habit of running out.