Hope Under Attack is Episode 4-1 of Trauma Center: Under the Knife and Second Opinion. It's a story-only episode.
Story[]
After Reuben is rescued in Rubora, Derek receives a telegram from Dr. Miller of Caduceus Europe informing him of Greg Kasal's GUILT infection. Derek rushes back to Caduceus and demands to know the condition of his mentor. Sidney Kasal tells him that at the moment, Greg is in stable condition. While Derek was away, there was an outbreak of GUILT and Greg had been infected while treating one of the patients.
Derek goes to speak with Greg and learns that there was a suspicion from Greg himself that he had been infected with GUILT. Sidney and the other members of Caduceus learn that there are immature versions of Greg's GUILT that can be used as antigens for the serum that needs to be made to treat Greg's GUILT.