Years later, grown-up Quinn (played by Christian Bale) runs a stone-made castle in England, a lonely bastion of mankind, afraid of the sky and the dragons that could attack any time. Their only faint hope is to outlast the dragons, wait until they die out again (as they presumably did several times before) and go into hibernation.
Comes along Denton Van Zan (played by Matthew McConaughey), leader of a US army unit from Kansas, bringing a tank and a helicopter, piloted by Alex (played by Izabella Scorupco). Mistrusting, but needing each other, the two leaders Quinn and Van Zan work together and eventually manage to kill one of the dragons.
After that, Van Zan tells Quinn that all dragons his unit has encountered so far are female. Their theory is that there is only a single male within the whole dragon population world-wide, who fertilizes the eggs the females lay, which explains the extreme growth rate of the population. They suspect that the male dragon lives in London, and they are on a mission to kill it and, thus, the species.
When Van Zan starts recruiting for his mission among the castle's population, a fight breaks out between him and Quinn, who still prefers to outlast the dragons. Van Zan and his unit go for London and are attacked by the male dragon on their way, leaving Alex and Van Zan as the only survivors. The dragon backtracks their route to the castle and destroys it as well, but the inhabitants are saved in an underground shelter.
Defeated, Van Zan returns to the castle, accepts Quinns lead, and the three go to London. Quinn leads them to the male dragon's hiding place at the underground construction site, and they manage to kill it by shooting an explosive into its mouth just as it starts breathing fire. Van Zan is killed, and Quinn and Alex live happily ever after.