Desyatyrichna Yenni vpevnena, shcho yiyi molodshyy brat Tim — takyy samyy henialʹnyy detektyv, yak vidomyy Sherlok Holms. Dlya nʹoho nemaye tayemnytsʹ i neroz·hadanykh zahadok. Tsiyeyi zymy Yenni ta Tim upershe yidutʹ vidpochyvaty na lyzhnyy kurort, de yikhni batʹky prydbaly nevelychkyy budynochok. Khocha dovkola — lyzhni trasy y prekrasni krayevydy norvezʹkykh hir, Sulʹtoppen — ne zvychayne kurortne mistechko. Pid chas karnavalu v mistsevomu hoteli vykradayutʹ dorohyy perstenʹ z diamantom. Khto zh u Sulʹtoppeni — zlodiy?