The search for the fourth key has begun. Jack, Jenny and Justin set off, accompanied by Whiskers the tiger and Feathers the eagle. Also coming along on the mission is the latest, and the most unusual member of their group - Gloria, the ghost. As usual, Jack and Jenny are fighting with each other, as are Whiskers and Feathers. It's up to a harried Justin to act as an impartial referee to the battling couples. However, all is not well on the mission. They encounter a party of rats and have to make a detour through a creepy forest in order to avoid a confrontation. But their troubles are just beginning because, in the forest, they discover that something is stalking them. What the stalker turns out to be is quite a surprise, but another surprise is in store when they reach a bridge which connects to an island where the key is supposed to be hidden. A nasty creature awaits them on the bridge, but it appears to be an impossible reality. On the island, a mysterious monument is found, but it proves to hide a deadly secret. Luckily, Gloria is on hand to save the day, but she has to play a very dangerous game if she wants to rescue everyone.