Complex sentence: It picks up where "The People of Sparks" left off, during the Emberites' first winter above ground.the two children must go back to Ember to discover something that was lost and left behind.
Split into simpler sentences: It picks up where "The People of Sparks" left off, during the Emberites' first winter above ground. The two children must go back to Ember to discover something that was lost and left behind.