On their peaceful camping and cycling tour of the English countryside, the Five come across Richard Kent – the son of one of the richest men in the country! When Dick is mistaken for him and kidnapped, by Rooky, a dangerous criminal who had been a bodyguard in the Kent household, the children know they have two leads: Owl's Dene on Owl's Hill, and a Black Bently – KMF 102. The children's search for Dick leads them on a moonlit bicycle ride to the eerie mansion: Owl's Dene. What will they find there? And most importantly, will they be able to rescue Dick?
