It's 1972 and Gavin Moffat is 12. His father is the warden of the Loch Lomond campsite, a blessing and a curse for Gavin. He has to share his life with weekenders and tourists but he also gets almost unlimited freedom to roam with his friend Andy. This summer, the boys begin to spend time with Archie, an elderly resident of the site and accidentally discover a secret he's been keeping hidden in his caravan for longer than anyone will believe. But now Archie's time is coming to an end and he offers a deal. He needs their help to escape a sinister government agent who's closing in on him. In return, the full reveal of his secret and an adventure that will take them across Scotland - and across time.