The Greatest Fear - S2.E12

Able Squad arrives on Venus with the mission of locating and estimating every Neo base and troop concentration on the planet, as a prelude to invasion. While investigating a secret research facility Torres and Bronski are discovered, and in the battle to retrieve them Marsala is captured. He is taken inside, and sees that the facility is for research related to AutoMutation Syndrome (apparently a Neo sapien version of cancer). To prevent Marsala from divulging ExoFleet plans for an invasion Marsh sets out to destroy the facility with Marsala inside. Nara is unwilling to let Marsala be killed, and she goes to rescue him. She manages to succeed before Marsh finishes demolishing the complex, and on their way out she and Marsala unwittingly capture an experimental subject that merged with the Neo mega Lysander.