1340 年代,葡萄牙與西班牙慣性選擇政治聯姻,只為穩固雙方的國家情勢。然而葡萄牙王儲 Pedro並未對自己的新娘 Constanza 心動,而是對她的侍女 Inês de Castro 一見鐘情。Pedro 還是奉父王之命成婚。但他對 Inês 的熱情並未消逝。兩人的愛情讓 Pedro 的爸爸當時的葡萄牙國王 Afonso IV 憤怒異常而將把 Inês 趕出宮放逐。
但1345 年時,Constanza 難產而死,Pedro 順理成章將 Inês 接回宮中,而 Inês接連替Pedro產下四個孩子。宮中流言四起,葡萄牙國王生怕怕葡萄牙與西班牙兩國反目成仇,因而派了三個刺客在 Pedro 外出時刺殺 Inês。
當時Inês 正與孩子在一起,所以等於在孩子面前殺了他孩子的母親。Pedro 接到惡耗後,憤而討伐父親,葡萄牙陷入動亂。兩年後,葡萄牙國王 過世,Pedro 成為葡萄牙領導者。
Inês de Castro ([iˈneʃ dɨ ˈkaʃtɾu], Inés de Castro in Castilian; 1325 – 7 January 1355) is best known as lover and posthumously-recognized wife of King Peter I of Portugal. Her dramatic frenetic relationship with Peter I was forbidden by King Afonso IV. Ultimately, she was murder at the orders of Afonso, which triggered Peter’s bloody revenge on his father.