Lynn Allen 
Adventures in the Sphere — The Missing Goblet [EPUB ebook] 

Aria discovers an unusual picture in her grandmother’s attic which somehow transports her to a small island in the middle of the ocean where she is met by a little sylph called Jenn. Jenn asks Aria to help to find a missing goblet which has been taken from Rathnid, a powerful gnome who lives inside the mountain which towers over the centre of the island. Rathnid had captured the sylph queen and won’t release her until his goblet is returned to him. Will Aria be able to find the goblet and return it to Rathnid? Will she be able to help to free the queen of the sylphs? Will Aria ever find her way back home tp her grandmother? Along the way Aria has numerous adventures and meets some very interesting characters.