How do you keep a moody, anxious and boastful ghost hidden from Grandma and Grandad when you're all holidaying together in a little caravan? 

This is the problem that faces Tom and Bella when they encounter the ghost of a Roman soldier and promise to take him with them to Rome. He's spent centuries shivering on Hadrian's Wall, dreaming of home; but the trouble is he's a very awkward traveller and he doesn't always seem grateful for the children's help. Getting him back to Rome and the sunshine he's missed for so long turns out to be much more complicated than they thought. 

Their holiday trip with the caravan brings them face to face with dangers they hadn't bargained for, such as sea monsters, haunted ruins, and highwaymen - not to mention Grandma's cooking. And it doesn't help that the ghost has demons of his own to deal with. Or that, as they get nearer to their destination, the family is about to run into really serious trouble of quite a different kind...