Nunca te sueltes (Never Let Go)

A distraught mother and her two children live in a cabin in the woods under the influence of an evil spirit. They need to be connected at all times, clinging to each other, even to the point of tying themselves together with ropes. But, when one of the children starts to question whether the evil is real, the ties that bind them together are broken, triggering a terrifying struggle for survival.