When the fabulous Lens of Hope goes missing from a Mouse Lighthouse, ships bearing a year’s supply of cheese for mice everywhere are put in danger. Without the Light to guide them, they will crash on the rocks. So the Trekkers must navigate a ghostly dark ships’ graveyard to find the Lens and restore it to the Lighthouse Keeper in time to save the ships. But Mo’s fear of the dark, and his efforts to fight it, threatens the Mission. It is only when Mo understands that his friendship with the Trekkers offers a light in the darkness for him always, that he conquers his fear and bravely returns, just in time, the Lens to the Lighthouse.