Isabelle kept a diary inside her mirror desk. In her diary, it reveals the forbidden romance between her and Samuel and her pain when she get's abused by her father or Franco. Isabelle left her diary once in The Ruins and found by Samuel. He replied to Isabelle's diary and he give it back to her. Later, her diary got almost burnt after her first mansion was on fire. Even if the diary is burnt, she still keep it. The diary was kept on the basement of the Hidalgo mansion for all those years.
Years later when Gabriel and Andrea visited Salvacion, they visit the Hidalgo mansion where Franco and Isabelle are residents back then. Andrea sneaks into the basement and discovered Isabelle's diary. She kept it in her slim bag for long. Back at Manila, she read everything inside the diary and it reveals the forbidden romance between her mother and Samuel. When Isabelle found Andrea, she gave the diary back to her mother.