Louella lives on the edge of a forest. But this isn't just any forest – this forest has unicorns in it! Louella's unicorn is called Norrie, and they love collecting shells together from the stream and spending all day together. Norrie’s special power is being able to cast a bright beam of light – so although Louella’s biggest fear is the dark, she never has to worry with Norrie around!

Until, one day, when Louella’s school has a class trip into the forest and Norrie doesn’t appear. Where could Norrie have got to? Can Louella overcome her biggest fear to help her friend out?