Voyager inadvertently trespasses into subspace corridors under the control of the Turei. The Turei demand access to Voyager's computers in order to wipe out all information concerning the corridors, which Captain Janeway declines. The Turei vessel respond by firing on Voyager, crippling the ship and forcing it to land on a nearby planet. The planet is the home world of the Vaadwaur, the ancient enemy of the Turei. The crew of the Voyager discover several hundred Vaadwaur in stasis tubes; they awaken the Vaadwaur and are told how the Vaadwaur were the victims of the aggressive Turei and their allies. Voyager plans a joint venture to escape the planet and the Turei fleet now orbiting it. After Neelix discovers that the name 'Vaadwaur' appears in his people's ancient language as a word for 'foolish', the crew learn of the Vaadwaur's violent past; it was in fact the Vaadwaur who were the aggressive species, and they are plotting to become the dominant species in the region once again. Captain Janeway realizes what the Vaadwaur are planning, so she decides to limit the number of armed ships they would use in the operation. The Vaadwaur reply by attacking Voyager with several squadrons of attack craft.
Voyager is forced to make a rapid ascent through the planet's atmosphere, while under heavy fire from the Vaadwaur fighters. Despite poor sensor performance and eventual battle damage to the targeting sensors - which forces a switch to manual targeting - Voyager performs amazing feats of targeting during the battle, scoring direct hits even when firing three arrays simultaneously. Voyager, although formidable, is nearly overwhelmed by the sheer number of Vaadwaur vessels. Voyager contacts the Turei forces orbiting the planet and assists them in targeting the Vaadwaur ships, giving them time to get out of the planets thermosphere and engage warp drive. The Turei and Vaadwaur fleets are left to battle each other.
Seven of Nine noted before the conclusion of the episode that 53 Vaadwaur ships were able to avoid the Turei and escape through the subspace corridors. Captain Janeway said that given their aggressive nature, Voyager may not have seen the last of the Vaadwaur.