The Greatest Kingdom Ruby's group lands in Mantle, the city below Atlas, but become uncertain of Ironwood after seeing the state of the city. Maria takes the group to Dr. Pietro Polendina, who informs them of Ironwood's increasing paranoia following the fall of Beacon. While Ruby's group fends off the invading Sabyrs, they are assisted by Penny, who is revealed to have been repaired by Pietro and now serves as Mantle's protector. However, Ruby's group is arrested by the Ace-Ops, a group of elite Atlas huntsmen.