The land of Roar

"When Arthur and Rose were little, they were heroes in theLand of Roar, an imaginary world that they found by climbing through the folding bed in their grandad's attic. Roar was filled with things they loved--dragons, mermaids, ninja wizards and adventure--as well as things that scared them (including a very creepy scarecrow). Now the twins are eleven, Roar is just a memory. But when they help Grandad clean out the attic, Arthur is horrified as Grandad is pulled into the folding bed and vanishes. Is he playing a joke? Or is Roar--real?"--OCLC.