Constanza,princessofSpain,meetsPedro,herpromisedhu*andandfuturekingofPortugal.Amidstpoliticalintrigue,PedrofallsinlovewithInès,Constanza'said.InèsreturnshastilytoSpain,repressingherownfeelings,butConstanzadiessuddenly.Pedrogoesagainsthisfather'sdecisiontomarryacrownedgirl,andreuniteswithhislovedone.ThreePortuguesenobles,actingincollusionwiththeking,persecuteInèsinapalace,andkillherbythesword.Theprince'sfactionisatthevergeofwaragainsttheirownking,buttruceisreachedatOporto.Pedrosulksinagonyuntilhisfatherdies;then,heobtainstheextraditionofInès'killers,andexactsterrificvengeanceuponthem,beforecrowningInèsasqueen,posthumously.