Recommendations based on "Die drei ???. Spuk im Hotel. (Ab 10 J.) (drei Fragezeichen)."

Fünf Freunde erforschen die Schatzinsel - bk1557; C. Bertelsmann Verlag; Enid Blyton; Paperback; 1900

'This summer the Five will become six--and George isn't happy about it. American girl Berta has been threatened with kidnap, and Kirrin Cottage is the only place she can hide. But Berta's arrival puts them all in danger when someone starts spying on them from Kirrin Island. Berta may be in disguise, but can they keep her safe and protect her from the kidnappers?' -- Back cover.