Left 4 Dead - Sacrifice

PART ONE:

The Sacrifice: Part One covers events from the end of Blood Harvest as the Survivors are fighting their way to the Armored Personnel Carrier sent by the Military. A small flashback revealing the past of Louis during the Green Flu is shown, along with his first encounter with the Infected.

In the present, the Survivors have made it, but their first direct encounter with the Military isn't exactly friendly, as not only are they referred to as "Tango Mikes, " but instead of the Echo Safe Zone they thought they were heading to, they are now heading to Millhaven, a location unknown to the Survivors. Upon disembarking, the Survivors are ordered at gunpoint to leave their weapons behind and are marched out of the vehicle where they are met with aggressive military personnel, who immediately do not get along with Francis. A military personnel tells them they are going to "testing", to which Zoey reacts nervously.

PART TWO:

The Sacrifice: Part Two continues on from Part One. Two days ago in Millhaven, Sergeant Downey and Lieutenant Mora are discussing the radio silence from command, where word has not been heard from over six days, along with the safety of the compound. In the present day, Louis and Francis are locked up together in a sealed room with independent ventilation, where Francis fails at agitating the military personnel in order to escape. However, they call Louis over, and ask about the mutating Infected, upon which Louis is surprised they have never seen the Special Infected. While Louis is explaining what the Smoker is, Lt. Mora is explaining the Hunter's details to his superior, Major Everly, who does not believe him; nor does he believe that there is a distinction between Carriers and Survivors, whilst Lt. Mora believes all carriers should be killed.

Meanwhile, Zoey and Bill are held under armed guard in a medical examination room. Zoey is coerced into supplying a saliva sample to the doctor, but the threatening behavior involved on the part of one of the guards named Rivera allows Bill to create a distraction which gives Zoey an opportunity to overpower Rivera. However, she releases him when he goes into an inexplicable blind panic, at which point the doctor intervenes and explains the situation. He drops the bombshell that the Survivors are fully infected but asymptomatic Carriers, which means that they have been unwittingly spreading the Infection all over Philadelphia. He also states that no cure is as yet available. Delving deeper into the infection's epidemiology, the doctor explains that the Carrier gene runs on the father's side. Coming right on top of the moral dilemma posed by being a Carrier, Zoey is then psychologically overloaded by a flashback to the time when, two days after the first Infection, she killed her beloved father in the mistaken belief that he would "turn" after having been attacked by her mother. She now realizes that her father was an immune Carrier and that this tragic action was unnecessary. Back to the present, the doctor asserts that he is the only one standing between them and summary execution as infected Carriers. Just after the doctor concludes with a plea that they all help each other escape, a loud alarm goes off in the facility. Lt. Mora has mutinied, relieved Major Everly of command during which process the alarm was tripped. Unfortunately this has enraged all Infected within earshot and the facility becomes the instant focus of their overwhelming attack.

Back in their cell, Francis and Louis who also hear the alarm and know instantly what this foretell