Spooky animation leads viewers and David into the ""dark caves of the geometer."" But geometry isn't that mysterious. They are passionate for simplicity. Under ideal conditions, geometers will frown at color, movement, sound, and all the other elements that make the real world too complicated. David touches up on a geometric concept here and there, including congruent objects. In the end, he reintroduces geometry as a puzzle.
David starts out as the captain of a ship trying to navigate through dense fog and a dense lad in the crow's nest. It's at this point that David underscores the importance of direction. He demonstrates the line segment (with his artm) and explains that certain claims about geometry can't be explained. Assuming, like all geometers, that a straight line is the shortest distance between two points, David begins to navigate the waters around him. This segues into the concept of angels, and the need to be more accurate than just ""left"" and ""right.""
A medieval David talks about intersecting lines and the angles they form. He visits an archaeological site to learn about triangulation and theodolites.
Starting out on a railroad track, David explores parallel lines. He needs to straighten the railroad ties so he can ride them easily. With a geometry book in hand, he reads: ""If a line and a point are drawn on a flat plane,...only one line can be drawn so that it never meets the other line."" But he also needs to understand corresponding angles and parallelograms to get the two rails precisely the distance apart he wants.
David talks about ""the geometry of not-falling."" It is rooted in the right angle. Fighting gravity depends on building things at right angles. But how do you ensure a proper right angle? David moves up in tools, from the spirit level to the theodolite. Interwoven in this program is the Pythagorean Theorem and the first glimpse of what would become the Chunnel linking London to Paris — ""a straight line that starts by going down and ends by going up.""
David goes to the mountains on a new expedition: trianguleering. His mission is to find triangles in nature. He partially succeeds by showing off an isosceles triangle — one with two equal sides. But to those who want a bigger challenge in trianguleering, David suggests searching for certain angles. He explains what the angle of repose is, and then illustrates how easy it is to copy triangles from place to place.
The word ""tile"" comes from a Latin word meaning ""to cover."" Why cover with tiles? ""It's not the tiles that are important,"" David explains. ""It's the cracks."" The cracks and crevices in tiling can serve as waterproofing or drainage, or even weight-saving. Still, people think in terms of tiles, so David examines complex patterns on snow tires and the Tangram puzzle.
Life is change, and as David changes, he introduces transformational geometry. It boils down to three patterns: translations (slides), rotations (turns), and reflections (flips). David also explains the ""know-it-all"" approach to constructing shapes, aided immeasurably by the Cartesian plane.