Some dying stars do more than fade quietly; they can unleash gamma-ray bursts capable of sterilizing a swath of the galaxy thousands of light years wide. This episode of The Universe surveys the stars astronomers watch most closely for that reason. WR104, a Wolf-Rayet star roughly 8,000 light years from Earth, gets particular attention for its spiral shape and the possibility that its rotational axis points toward our solar system. The program also visits 3C321, nicknamed the "death star galaxy" after one of its black holes fired a beam of radiation directly into a neighboring galaxy, and holds it up as a cautionary example for the Milky Way. Closer to home, Eta Carinae and Betelgeuse serve as case studies in stellar instability, both massive enough to end their lives in supernova explosions within astronomically short timeframes. Footage combines telescope imagery with computer-generated visualizations of these stars and their surrounding nebulae, and astrophysicists explain the mechanics of gamma-ray bursts and what would happen if one were aimed at Earth.