It's a race against time as Darius must accelerate his plan to stop the asteroid before the Pentagon shuts him down. Also, Grace has to make difficult decisions that could have life or death consequences for millions of people, and Liam and Jillian reunite under surprising circumstances.
Did You Know?
Darius does not want the Pentagon to use the impactor to break the asteroid up, because he wants to use the EM drive to launch a probe to act as a gravity tractor to pull the asteroid off course. But if the gravity tractor can pull the whole asteroid off track, it will apply the same acceleration to the fragments of a broken asteroid, so there is no reason not to use the impactor first in case the gravity tractor never gets into position. See more
References Annie Hall