Hekja and her dog Ricki Snarfari (Mighty Rover) live a simple life in their small coastal village. She adopted him when he was an injured puppy, and thanks to her help, he recovered and became strong. They are both taken as prisoners when Vikings attack and must adjust to living in a world wider and grander than either of them ever dreamed of. Hekja is found to have a talent as a message runner, which causes the bold Viking woman Freydris Eriksdottir to make her her servant.

They face hard work and tragedy, but prove themselves and brave as the Vikings on a journey that will take them to Iceland, Greenland and even further.

This book was originally published in Australia under the name "They came on Viking Ships", the title was changed to "Slave Girl" in the UK and "Rover" in the USA.