Call it luck, or call it fate, each member of the fellowship has had more than their fair share of close calls across the course of their journey to get the ring to Mordor in Lord of the Rings. Whether it’s narrowly evading capture by a vicious band of orcs, barely surviving a deadly encounter with a group of wargs, or the many battles they survive, every one of the companions has had some near-misses that could have changed the outcome of the entire quest, and the fate of Middle Earth as a whole. Luckily for the heroes of the story, these ‘skin of the teeth’ moments usually work out favorably, and end up with them getting to where they are meant to be, even if they took the long way round. This is one of Tolkien’s core themes in all of his books: Good always prevails.
However, for the villains of the story, these narrow escapes never work out quite so favorably. Often it is the character’s own hubris, selfishness, lack of foresight, or greed, that ultimately leads to their undoing, and these times usually end up with the good and kind-hearted characters gaining the upper hand and barely avoiding the awful fate that the villain had in store for them. There are lots of examples of this in the books; for example, Sauron’s self-assurance that no one would ever be able to resist the power of the One Ring meant that he couldn’t possibly conceive of or prevent his own defeat. There is, however, another villain who made a disastrous error.
Arguably, one of the most prevalent and painful examples of this hubris is Saruman’s big mistake, a decision that cost him the entire war of the ring: capturing and confessing to Gandalf. There are so many reasons why it was fundamentally foolish for Saruman to lure and trap his old friend in the tower of Orthanc in Isengard. The most obvious of these reasons is that Ganadalf never would have suspected a thing if Saruman hadn’t confessed his delving into the Palantir and his desire to find and own the one ring to join leagues with Sauron.
When Gandalf first arrives at the tower, he is there seeking council from an old friend. He currently believes that Saruman is still on their side, and has not even the slightest inkling of doubt in his mind. Saruman’s first mistake is revealing his grand plan to the wizard, and trying to persuade Gandalf to join him. He should have known that the morally just and kind-hearted Gandalf would never betray the peoples of Middle Earth to help Sauron, because protecting them is the very mission that the Istari were put on Middle Earth to achieve.
The second mistake that Saruman makes is underestimating Gandalf once the truth has come to light. Even though the grey wizard refuses to turn tables and join the side of evil, Saruman should have done something more concrete at this point than locking Gandalf up on the top of the tallest tower. In assuming that Gandalf won’t be able to find a way down from the tower in time to save and to warn Frodo of the terrible black riders coming his way, Saruman leaves him unguarded.
However, Gandalf has many old friends in the world, and many alliances. In underestimating his abilities and his connections with others, Saruman both neglects to realize that Gandalf will inevitably escape, and also fails to guess that he would have a backup plan to protect Frodo and the Ring from exactly this sort of nefarious interference (namely, Aragorn). From the moment Gandalf escapes the tower, carrying the knowledge that Sauron is a traitor who must be stopped, the white wizard’s plans are doomed, and he has essentially undone his own chances of success.
If Saurman had never tried to preempt things, and had just let it run its course, there’s a strong chance that Gandalf may have led the fellowship straight to Isengard, in the hopes and trust that Saruman would help them. Even if it had not been Isengard, it may have been Rohan instead, where Saruman still could have claimed the One Ring through his control over King Theoden, and the slimy help of his Rohan servant Grima Wormtongue. But instead, his pride led him to tell Gandalf of his terrible intentions and try to enlist the grey wizard in helping him achieve them. This one big mistake to reveal his plans too early, and cost him the Ring literally falling right into his lap. Ultimately, it ended with him in exile from his home in Isengard, on the run, and then eventually killed in The Shire for his devastating interference.