The "Previously on Battlestar Galactica" section includes two scenes which were not in the previous episode: civilian refugees are seen boarding Galactica and entering the starboard hangar deck as Chief Tyrol says that Helo has been transferred to the deck to manage them; in the command center, Gaeta informs Adama that there are a 51 Sagittarons in the Thera Sita inhabitants coming aboard, which leads Tigh to utter, "Oh, Boy," and Adama to say, "Helo may be overmatched down there."
A sickness has broken out amongst the more than 300 displaced civilians forced to live aboard Galactica in the unused starboard hangar bay which has been nicknamed "Camp Oil Slick" and later "Dogsville". Part of the hangar has been sectioned off into a medical ward where Captain "Helo" Agathon helps direct the sick to beds while a Caprican physician, Dr. Michael Robert, examines a boy named Willie King. Willie's mother causes a scene when she protests Dr. Robert's examination, stating their Sagittarion faith rejects modern medicine. Dualla, a "Sag" herself, tries to convince the Kings that Robert is here to help them, but Mrs. King seems overly terrified of Dr. Robert.
On Colonial One, President Roslin meets with her aide Tory Foster and Vice President Tom Zarek to discuss the trial of Gaius Baltar. Zarek believes that Baltar's trial could stir chaos within the fleet and warns of assassination plots and riots. He strongly advises Roslin to declare martial law as a precaution during the trial. When Zarek leaves, Roslin and Tory note that Zarek seemed extremely worried about possible unrest.
Aboard Galactica, Roslin meets with Admiral Adama, and Dr. Robert explains the sick have Mellorak, a virus which first attacks the kidneys and later other organs in the body. Dr. Cottle further assures them that Mellorak, while contagious, isn't airborne and is passed only by human contact. If the patients are kept quarantined, there is little risk of an epidemic. Cottle says it is treatable with the vaccine Bittamucin, but only if administered within 48 hours of symptoms. Robert states his agitation of the Sagittarion's refusal for medicine saying they'd rather turn to archaic roots and herbs to cure them. Colonel Tigh shares Robert's resentment of the Sags, calling them a useless and backward people. Because of the shortage of Bittamucin, Robert believes he should ration the drug only to those who display symptoms. Roslin tells Robert to do what he can for them, regardless of their faith.
In Joe's Bar, Dualla and Apollo sit talking with Chief Tyrol, Felix Gaeta, and Racetrack about the current situation. Tyrol shows his animosity toward the Sagittarons by making alcohol-fueled comments about how they refused to fight on New Caprica and that they don't deserve medical treatment. Apollo reminds him that Dualla is a Sagittarion and tells him to "cool it". Starbuck, who is drinking nearby, has an amused chuckle.
Meanwhile in the brig, Athena meets with Caprica Six who offers words of consolation and encouragement and states that her best chances lie with helping the humans. In an adjacent room, Roslin and Tory watch the discussion through one-way glass. Athena tells Caprica Six that she will see to her being treated fairly during Baltar's trial, but suddenly, Caprica Six's imaginary Baltar appears who asks about Caprica Six's desire to help the humans, speculating that she perhaps wishes to become one of them. Athena leaves saying she will return later with a change of clothes for her. Caprica Six talks to Baltar and they engage in a kiss. When Tory asks what she is doing, Roslin states she's seen this before, that she believes Caprica Six is communicating with someone they can't see.
Elsewhere, Helo deals with an angry group of Sagittarions in a crowded room. They are furious about their treatment under Robert, with several of them calling him a murderer and saying he killed Sagittarions back on New Caprica. Helo believes they are overreacting until Mrs. King pushes her way to the front to inform Helo that her son Willie is dead. Helo believes the Kings waited too long for treatment, but the woman tearfully says her son had the symptoms for only 12 hours.
Later, Helo takes the news of Willie King to Admiral Adama, and Colonel Tigh. He says the Sagittarions are accusing Dr. Robert of singling them out and killing them back on New Caprica. Adama has his doubts, saying Dr. Robert is a respected physician. Helo believes the accusations should be taken seriously and requests Cottle to at least check the records. Adama suggests he let the matter rest and dismisses him.
Helo leaves dejected, and Colonel Tigh angrily follows, confronting him in the corridor. Tigh says Robert is a trusted friend of his and he won't allow Helo to tarnish his credibility. He tells Helo to consider his own situation before he judges others. Helo knows Tigh is referring to Athena and furiously punches Tigh in the face. Guards rush up, but Tigh tells them to stand down, saying he's at least impressed that Helo is still a "man". He adds that this "little incident" isn't over and walks away, leaving Helo uneasy.
Helo returns to the ward where he gives Mrs. King a religious bracelet Willie wore. She thanks him, adding that Dr. Robert's hatred of the Sagittarions has made him a killer. In explaining the atrocities he carried out on New Caprica, she conveys her fear they will all die if he gets his way. Helo is shaken by her claims.
Next, Helo is alerted by his wife Athena that their daughter Hera has fallen ill. Athena informs Helo that Hera had already been taken to Dr. Robert. Helo rushes as Robert sticks a needle in Hera and asks if this is really necessary. Robert comforts the child, saying everything should clear up in a few hours. He notices Helo's anxiety and asks if there is a problem. Helo pulls his wife and child away, leaving Robert confused. In their quarters, Helo tells Athena about the accusations against Robert and wonders whether Robert also has a grudge against Cylons. To her parents' relief, however, Hera seems fine after her treatment. Nonetheless, Helo is determined to find the truth.
Helo marches down to medical, finding the lights off and no one around. He proceeds to a stack of medical files and begins reviewing them. He finds nearly 90% of the Sagittarions under Robert's care back on New Caprica died, even from the most trivial conditions. Helo is startled by Dr. Cottle, who is furious that Helo won't let the situation go. Helo slams the reports down and demands Cottle look for himself, pointing out that a Sag went to Robert for a broken arm and then suddenly he's pronounced dead hours later. He gives other examples of Sag after Sag dying suspiciously. He begs Cottle to conduct an autopsy on Willie King, to which Cottle says he already had, finding nothing but the antibiotics Robert injected him with. Defeated, Helo relents and walks out.
In the meantime, Dualla, feeling sick herself, asks Dr. Robert to help her. He gives her an injection and she lies down in a bed. At night, Mrs. King informs Helo of Dualla's illness. She is accosted by the guards but Helo rushes down to the hangar ward and finds Dualla lying motionless on a bed. He tries to revive her, but she is unresponsive. Helo tries to carry Dualla out of the infirmary but is intercepted by Dr. Robert. Robert refuses to let them leave and calls the guards to stop them.
An angry Colonel Tigh and Dr. Cottle arrive in the hangar bay. Robert demands that Tigh have Helo arrested, but Tigh shouts at a surprised Robert. Cottle admits that due to fatigue he had not viewed Willie King's bloodwork until a few hours ago; the test had uncovered a deadly toxin in the boy's body and no trace of Bittamucin. Robert had indeed killed him. Robert defends himself by saying that the sick Sags would have died anyway and that by giving them deadly toxins he was shortening their suffering and saving Bittamucin for those more valuable to the fleet. He looks to Tigh for support, saying that he thought Tigh's hatred of Sags was second only to his hatred of Cylons, but Tigh replies that what he hates is being wrong. Tigh tells Helo to arrest Robert.
As Robert is marched out of the hangar bay, Helo meets Mrs. King's gaze as she stands in the crowd. After receiving Admiral Adama's apology, Helo returns home to his wife and daughter.
The episode ends with a brief extra scene of Helo admitting to Admiral Adama that he is responsible for the deaths of the infected Cylons (see "A Measure of Salvation"). Adama asks him if he really wants to be confessing this. Helo replies, "Yes, Sir."
Adama explains that if Helo wishes to proceed, he will have to get a written confession. Helo will most likely face a court martial, and, if convicted, possibly a firing squad. Adama asks again if Helo wants to continue with his confession, to which he responds, "No." Adama dismisses him.