Thirteen-year-old Martin and his younger brother Charlie are on a very special journey. They're going to be travelling 421 miles all the way from Preston to the very tip of Cornwall. They're hoping to catch a glimpse of the dolphin that regularly visits the harbour there. But is that the only reason they are going?

It's a journey that's full of challenges and surprises. Martin adores his brother Charlie but he's not like ordinary kids. He's one in a million. He was born far too early, and ought to have died. And cheeky, irrepressible, utterly unique Charlie is always keeping Martin on his toes - especially on this crazy trip they are now on. Martin is doing his best to be a good big brother, but it's hard when there's something so huge coming once they get to Cornwall ...