Collateral Damage (S03E02)

With hostilities escalating between the resistance and the alien invaders, Tom calls on nuclear specialist Roger Kadar (guest star Robert Sean Leonard), an obsessive but gifted scientist who runs the local power grid and lives underground, earning him the nickname of "The Rat King," to come up with a plan that will strip the aliens of their power. As suspicion continues to mount about a mole within the resistance, Tom and his leaders make a drastic decision that jeopardizes trust among the group. Anne, meanwhile, has a feeling that all is not right with her newborn. (Warner Bros. UK)