Strange things are happening in the basement of an old house in East London -- and not for the first time. The floor has parted, forming a kind of channel, and faces from the past are floating in it in an endless stream.
From the gap, a familiar voice is calling out -- to 12-year-old Tom. It called to him when he was last here 10 years ago. Now that he's back, the voice is, too.
Tom's mother has cancer, and the two of them are paying a much-postponed visit to his estranged grandmother. It isn't exactly a joyous family reunion. If this weren't enough to make a boy Tom's age wish he were someplace else, there is someplace else Tom is needed more -- and it's from there that the voice is calling him.