A school organization heads off to a Holy Week retreat, led by their religion professor.

Nights later, the kids transform themselves into their real form as tiyanaks with elemental powers of water, air, and land, who attack the group, killing and disabling them one by one, until only the professor, the mother and her son, and some students remain.

The students kill two of the tiyanaks with holy relics but fall short when dispatching the last of them.

Days later, the survivors have a party when Sheila checks on Biboy who contracted a fever.

When they try to find out what happened, the boy's eyes become fiery and enraged, and his head becomes engulfed in flames, revealing himself as a tiyanak.