Friday Barnes has a new case, and this time it's personal! When Friday's father turns up out of the blue, he brings his daughter some distressing news - Friday's mother has been kidnapped! But who would want to kidnap a theoretical physicist? The Headmaster needs Friday's help too, when Highcrest Academy is thrown into chaos by the arrival of a beautiful new student - Princess Ingrid of Norway. She's rich, she's royal and she's got her eye on Ian Wainscott. Despite heightened security at the school, things start to go missing. It appears Highcrest Academy has been infiltrated by a master thief, The Pimpernel. Can Friday crack the case of her missing mother, reign in a royal brat and unmask the elusive Pimpernel? If it means she gets to ditch PE, then of course she can!