Sonic and the gang visit one of the biggest and most ancient caves in all of Mobius for a Summer activity. What started off as a harmless, self-guided tour, soon became a danger to their lives. The gang becomes split up, as the roof begins to cave in. They must go on a journey to find each other again and find their way out, without cell phone reception, or a map. When Sonic and Shadow get stuck together, they may find that they work better together than they thought, perhaps in more than one way.