Cirith Ungol, the dark crevice in the mountain at the top of the steep staircase, was originally protected by Isildur and the men of Gondor, where they built a tower to prevent evil pouring out of Mordor into the fields of Ithillien. During the time in which Isildur was succumbing to the allure of the ring after the Battle of the Last Alliance, Shelob the Spider demon inhabited the cave and filled it with her malice. The tower fell into the hands of the enemy, and all manner of evil creatures came to reside there.
During the 2001 film adaptation of Return of the King by Peter Jackson, the audience sees Gollum lead Sam and Frodo up the steep staircase towards the evil crevice. The film uses the device of Lembas bread, scattered craftily by Gollum to frame Sam for greed, in order to split the two companions up. Frodo ventures forth into the spider's home alone, and Sam travels back down the stairs, only to find the remnants of the elven food, and realizes the peril of his dear friend. He rushes back up the cliff to defend Frodo, and there he finds the glowing sword Sting which was gifted by Bilbo, and the light of Elendil, which was gifted by Galadriel. Using the two lights, he is able to find his way through the darkness and defeat Shelob in battle. However, he fears it is too late, as he finds Frodo paralyzed by the spider’s sting. Fearing him dead, Sam removes the ring and the chain it is carried on, and hides just in time to see Frodo carried off by orcs, up into the tower.
The orcs converse as they move the body, and it is revealed that Frodo is still alive, only stunned. Sam must then make his way into the tower in order to save his friend. But there is an evil that guards the gates to the tower, that neither of the hobbits were aware of. As the brave Samwise approaches the gates, he feels a power repelling him like a force field. It is described in the book that ‘They knew an enemy. Visible or invisible, none could pass unheeded. They would forbid his entry and his escape.’
By ‘They’, Tolkien means the Silent Watchers, two figures who are seated on either side of the gate, barring entry. Their will and their malice is so strong that it keeps out any who do not have an equally evil purpose. They have 3 heads each, to look in all directions and detect subterfuge, and each head is shaped like a vultures' skull, to deter the faint of heart, and represent their link to death. They have sharp claws, but they appear not to move at all, they are more of an expression of pure hatred than a danger in physical form, but they are able to hinder Sam in his journey nonetheless.
He is only able to break out of their cruel constraints thanks to the light of Elendil, which is a symbol of love and hope in dark times. The purity of the light, and for Sam's desire to rescue his most loved companion, is the only thing powerful enough to break their spell. But as it does, the Silent watchers let out a piercing shriek similar to that of the Nazgul, to warn the orcs upstairs that an intruder has entered their midsts. He is forced to put the ring on and make himself invisible so that he stands a chance of making his way through the tower and up to the tallest room in the turret, where he finds Frodo just regaining consciousness. Here, Sam freely gives back the ring, making him one of the few characters (alongside Faramir of Gondor) who is able to resist its power and let it go.
Together, the two hobbits must leave the tower and make their way to Mount Doom so that Frodo can throw the weapon into the fires where it was made, However, on their way back out of the tower, the watchers once again bar them, this time from leaving. They are in incredible danger, for if the orcs find them here, they will kill them both and take the ring, and the evil lord sauron will achieve his dominion over all of the land.
By sheer force of will, they are able to use the light of Elendil to escape one more time, and the force is so powerful that it destroys the watchers. Perhaps the spirits inside the watchers were once good, and were summoned peacefully by the Men of Gondor to protect the tower, and then twisted by the evil that seized it and trapped there evermore like the Army of the Dead. Or perhaps the spirits were evil from the start, and only imbued within the statues once Sauron had begun his evil reign. Either way, the spirits are set free by the light, and are able to leave Middle Earth, no longer to be contained within their motionless bodies.
