When the 12 Colonies of Man are wiped out by a cybernetic race called the Cylons, Commander Adama and the crew of the battlestar Galactica lead a ragtag fleet of human survivors in search of a "mythical planet" called Earth.
During the cylon attack on the planet, Serina and Boxey's dog dies while they're watching. The dog's death is also referenced several times as it actually plays an important role in the plot.