Niven is at his best in collaboration, and this is no exception. Building Harlequin’s Moon is is a story in many layers. The main plot line is about the first interstellar starship, escaping a Sol System full of renegade AIs and nanotech, escaping to reclaim humanity. But there is a malfunction and the starship is stranded in a barren star system partway to its goal. More antimatter is needed to refuel the ship, and the colonists refuse to use nanotech due to their belief that nanotech leads to evil. The only option is to spend sixty thousand years (yes it’s a long time but they can extend their lifespans indefinitely) building a habitable moon out of smaller ones, and then populating it with flora, fauna, humans, and then finally industrializing and constructing a huge collider to make antimatter. Rachel is a “Moon Born” “Child”, basically a slave to the goal of ultimately fueling the ship. But what no colonist counted on was that the Children are human too, and once the cogs in the plan are live humans, you have to look them in the eye. The titanic endeavor is ambitious in the extreme, but is it worth the cost to their souls?
On another level, the story is about Rachel, from her rather innocent teenage years to her coming of age as a leader of her people. And on yet another level, it’s about what makes us human. Our values, our biology, our goals?
The rather slow style of the book suits the story well, and events are followed in a careful fashion as we move, never too fast, through the action.
Building Harlequin’s Moon is full of wonderful three dimensional characters. Niven & Cooper ensure that even the most seemingly irrational and heartless protagonist is well understood by the reader as they delve deeply into her motivations. This novel shows humans at their best and worst, and it is impossible not to be entranced by the adventures of Rachel, Gabriel and the others. This is quite simply a masterpiece.