An unarmed human starship and its crew of fifteen hundred is destroyed by a technologically less advanced alien race, later called elves by the humans because of their resemblance to the mythical creatures. Other unprovoked attacks follow. All attempts to negotiate fail; the elves fire without communicating. Eventually, the overmatched enemy is driven back to his homeworld, but the conflict does not cease. The Alliance, one of the three human power blocs, ends up mired in a twenty-year-long war.
In all that time, humans get no closer to understanding why the elves fight or how to make peace. A few districts remain puzzlingly neutral, but when humans try to establish relations with one of them, it instantly joins the enemy side. In addition, not a single elf is captured alive; except for the very young, they have the ability to stop their hearts at will, and use it.