How long is a piece of string? The question sounds trivial until the film starts measuring, and the answer keeps changing depending on how closely you look. Mathematicians and physicists walk through the coastline paradox, the discovery that measuring Britain's shoreline with a shorter ruler produces a longer coastline every time, and trace that problem into fractal geometry, where shapes repeat their own complexity at every scale. From there the film pushes the idea of precise measurement to its physical limits, moving through quantum mechanics and the uncertainty that creeps into any attempt to pin down a particle's exact position. The strangest stop is the claim that measuring an object with enough precision could concentrate enough energy to collapse it into a black hole, a consequence of general relativity that the film uses to show where measurement itself breaks down. Animated diagrams and expert interviews carry the argument from a schoolyard question to the edges of physics, ending with the unsettling point that some quantities may be unknowable in principle, not just in practice.