AstheFifteenthDoctor,playedbyNcutiGatwa,takesovertheTARDISforhisfirstepicadventurehewillbejoinedbyRubySunday,playedbyMillieGibson,asshemakesherdebutastheDoctor’scompanion.　　TheepisodeseestheDoctorcomeface-to-facewiththemythicalandmysteriousgoblinsashislifecollideswithRubySunday,playedbyMillieGibson.　　LittleisknownaboutRubySundayasshewasabandonedonChristmasEveasababy.Nowlivingwithhermum,Carlaandgrandmother,CherryherworldisabouttobeturnedupsidewhensheencounterstheDoctorandthetwosetoffontheirfirstadventuretogether