Saint Bartholomew was one of the first disciples chosen by Jesus to preach his doctrine. Christian tradition tells that in a "fierce battle" he defeated the devil, overcoming all the temptations, deceptions, and superstitions presented to him. Valverde de Leganés has Saint Bartholomew as the patron of its parish. His day is celebrated on August 24. Coinciding with the tradition that tells us about the saint's victory over the devil, at midnight on August 23 (the beginning of Saint Bartholomew's day), our town had a traditional festival called "La Diabla", or rather: "The Escape of the Diabla".

There are two theories that underpin this tradition: one of these theories recalls the massacre of Calvinist Protestants that occurred on the night of Saint Bartholomew in 1572 during the Wars of Religion. The Catholics took advantage of the darkness of the night and disguised themselves in dark clothes, covered their faces, and armed themselves with clubs, pitchforks, knives, etc.

The other theory is based on Christian tradition. Saint Bartholomew was harassed by the devil with deceptions and temptations, engaging in a fierce battle between them, from which the saint emerged victorious. The tradition again confronts the two forces: that of evil represented by the Diabla, who escapes. And that of good whose protagonist, Saint Bartholomew, captures her again and makes her a new captive under his custody.

Essentially, parents told their children that they should be good, obedient, studious, etc., because otherwise, at that hour of the night the Diabla would escape and take them with her to the church tower where Saint Bartholomew kept her locked up all year, except that fateful night, in which that mistress of deceit, trickery, lies, and insidiousness, managed to outwit the trusting apostle. However, at the end of the night, the apostle defeated the Diabla and locked her up again.

There were some people that night, dressed in a long dark skirt, their heads covered with a black scarf, dragging chains and with a broom, who ran through the streets of our town, so that the children could verify the truth of it all, and occasionally they would bang brooms on the doors of the houses.

Today, a great spectacle is carried out in which during the night, the "Great Diabla", after escaping from the custody of Saint Bartholomew, and accompanied by a retinue of warriors and devils, roams streets and squares plunged in darkness, spreading fear and terror to locals and strangers alike, and using fire as her weapon against the "Altars of Life" and elements of the earth that had been placed in an attempt to drive away and keep the Diabla at bay. Once her journey through the streets of the town is completed, her entire entourage shows their power and veneration to the Diabla in a spectacle of fire and fights against the "Forces of Good".

In the Great Final Battle, the Diabla will have to face an angel sent by Saint Bartholomew to manage to escape from her captivity forever, but the "Forces of Good" end up defeating the Diabla and she is captured and taken captive to the church tower, celebrating the victory with a large bonfire around which both good and evil and numerous spectators dance.

Several thousand people witness the different episodes of this festival, in whose setup numerous volunteers and youth and friends clubs continue to collaborate in the development of the spectacle.

Since May 13, 2016, "The Escape of the Diabla" has been declared a Festival of Regional Tourist Interest.

The uniqueness and participation characterize this festival where children and adults recreate a part of the history of Valverde de Leganés.