Theresa Breslin 
Dream Master Nightmare [EPUB ebook] 

When Cy visits a special Viking exhibition in York and looks at a glorious Viking helmet, he is horrified to suddenly find a face in the helmet — his Dream Master! The Dream Master is in terrible trouble, a prisoner of Eric Bloodaxe — a fearsome Viking chief. Only Cy can rescue him. But first he must enter his dreams again . . . This is the second terrific adventure involving Cy and the Dream Master and is just as packed with action and wit as the first title.