The series tells the story of twin sisters Luna and Blanca and their journey towards discovering their ancestry and, at the same time, fulfilling their personal destinies.
The story of Luna Blanca begins with Rowena (Camille) who is believed to be the last descendant of Luna, the woman with a mystical twin shadow named Celestina.
Rowena grows up under the protective wing of her grandfather, Lolo Igme. She is clueless of her mythical roots and Lolo Igme would always warn her to be mindful of her surroundings.
Then, Rowena meets Luis (Raymart), the rich and kind-hearted unico hijo of Doña Consuelo (Marissa). Despite the extreme difference in their lifestyles, they fall madly in love with each other and their relationship grows even stronger with Rowena's pregnancy.
When Lolo Igme learns of Rowena's situation, he once again cautions her to be extra careful of the supernatural beings that inhabit their land. He tells that engkantos are believed to be most fond of pregnant women.
One day, Rowena gets lost while roaming in the forest. Engulfed in tension and fear, Rowena feels that a shadow is following her. Suddenly, she sees an unknown creature - a dark and terrifying engkanto! Panic-stricken, Rowena immediately faints upon seeing the dreadful creature.
When she wakes up, Rowena learns from the villagers that it has been a week since her disappearance. She slowly regains her memory and Rowena reveals that anengkanto raped her. No one would believe her story including Luis who vows to exact revenge. He sets off to the forest and comes face to face with the engkanto. He fights against the terrible monster and because of its powers, Luis will be banished to their realm.
Doña Consuelo's anger aggravates towards Rowena and blames her for Luis' unexplainable disappearance. Left with no choice but to leave their mansion, Rowena heads out to Manila to start anew. Meanwhile, she feels uneasy with her pregnancy and fears that it has something to do with her horrible experience with theengkanto. On the day of her delivery, Rowena gives birth to twin girls, but much to her bewilderment, the babies have different features -- one is a fair-skinned mestiza (Blanca) while the other one has a very dark complexion (Luna).
Rowena believes that Luna is her offspring from the engkanto. Because of this, she resents and neglects Luna but showers Blanca with her love and affection. Despite this, Luna doesn't harbor any grudge against her mother. The twins are likewise very close and inseparable. Luna is carefree and even becomes the protector of the weakling Blanca. Luna's shadow also turns out to be their friend and defender whenever someone bullies them.
However, the twins' life is about to change with Rowena barely making enough money to make ends meet. Because of her dire situation, Rowena decides to give up Blanca for adoption to Doña Corazon, a rich spinster who likes Blanca very much and treats her like her own daughter. Luna, feeling very sad about their separation, instructs her twin shadow to join Blanca and keep her safe.
How will the separate lives of Luna and Blanca affect their relationship? When the time comes and their paths cross again, will the sisters be able to discover their true identities and reconnect with each other? Will Rowena find it in her heart to accept Luna and acknowledge her as her own daughter? What will be Rowena's reaction if Luis comes back after being away for many years? Will Luis succeed in having a second chance at life and love?
