Anna and Diana square off in the dark bowels of the Mothership – Diana has been down there for 15 years and not had a single glimpse of Anna. Meanwhile, Erica has Tyler's blood analyzed, and learns the Vs did something sinister to her when she was pregnant with him.

Erica learns her partner, Malik, is a Visitor and must fight for her life – literally – to stop Anna from finding out she's Fifth Column. Meanwhile, Anna learns that Malik is missing and orders Ryan to find her, while Lisa realizes her body is beginning to change, causing her to become more and more like her mother.

After the radical faction of the Fifth Column murders three Peace Ambassadors, Erica goes on a mission to hunt down their leader, Eli Cohn, a former Mossad agent. Meanwhile, as Jack and other priests around the globe begin to speak out against the Visitors, Anna heads to the Vatican in an effort to convince the leaders of organized religion that the Visitors truly are "of peace".

Anna uses her newest gift to mankind, "Concordia," as a cover to hide an invading fleet of breeding vessels that will be used to ensure the perpetuation of Visitors for future generations. Meanwhile, Eli Cohn (guest star Oded Fehr) tries to convince Erica and the Fifth Column that the "Concordia" gala is the perfect time to assassinate Anna.

Anna, enraged at the increasing audacity of the Fifth Column attacks, enlists Ryan in an attempt to wipe out the Fifth Column in one fell swoop. Meanwhile, Father Travis, following Vatican orders, asks Jack to leave the church, and Lisa meets Diana, her grandmother – who Anna said was dead – for the first time.