Heatherpaw always knew the warrior code prohibited cats from different clans from meeting in secret, but one day, she falls for Lionpaw of ThunderClan. The young WindClan apprentice discovers a network of tunnels that lead underground from ThunderClan to WindClan territory, where they play at night. But Lionpaw becomes aware that he may not be making the right choice in being friends with Heatherpaw. Eventually, they must both make a difficult decision. Is their friendship really worth lying, breaking the warrior code, and keeping secrets from their Clanmates?