Tessa Mclean is lonely and unhappy. She never wanted to leave Inverkeld and go to live on Seagull Island and she doesn't like her father's new wife Sheena. Then one stormy night Sheena has an accident and Tessa is the only one who can help her. "Penguin Readers" is a series of simplified novels, film novelizations and original titles that introduce students at all levels to the pleasures of reading in English. Originally designed for teaching English as a foreign language, the series' combination of high interest level and low reading age makes it suitable for both English-speaking teenagers with limited reading skills and students of English as a second language. Many titles in the series also provide access to the pre-20th century literature strands of the National Curriculum English Orders. "Penguin Readers" are graded at seven levels of difficulty, from "Easystarts" with a 200-word vocabulary, to Level 6 (Advanced) with a 3000-word vocabulary. In addition, titles fall into one of three sub-categories: "Contemporary", "Classics" or "Originals".

At the end of each book there is a section of enjoyable exercises focusing on vocabulary building, comprehension, discussion and writing. Some titles in the series are available with an accompanying audio cassette, or in a book and cassette pack. Additionally, selected titles have free accompanying "Penguin Readers Factsheets" which provide stimulating exercise material for students, as well as suggestions for teachers on how to exploit the Readers in class.