Atthestartofhighschool,Piper,Sophie,IsabellaandHonorthinktheywillbebestfriendsforever,sotheysinkatimecapsuleinthelakewithalistofthingstheywanttodobeforegraduation.Bysenioryear,theyhavegonetheirseparateways.Piperhasturnedintotheclassclown,partygirlwhoneverpassesupadrink.Sophiepledgestostayavirginuntilsheismarriedandhascreatedapurityapp.Isabellaisthefeministfemmefatalewho'stheeditorofazine.AndHonoristheprideandjoyofthemunity.Herdreamofbeingaprofessionalballerinaistakingoff.Butwhentragedystrikes,theformerBFFsmustreunite,breakopenthecapsuleandpletethepre-graduationbucketlist.