《人鱼秘境第一季》ZacisateenageboywhodecidestocamponMakoIsland,unawarethatthreemermaids,Sirena,NixieandLyla,whoareguardiansoftheisland,arewatchinghim.Thatnight,whenthefullmoonrises,theboycomesintocontactwiththemagicwateroftheMoonPool.Thefollowingmorning,Zacwakesupdiscoveringhehasbecomeamermanwithafish-liketailandtheabilitytocontrolandmanipulatewater.Hisnew-foundmermanabilitieswillcauseproblemsforthemermaids.Thethreemermaids,curiousaboutlivingonland,aretransformedintohumanswhileinthemoonpoolduringafullmoon,nowhavingtheabilitytolivelikehumans.