Sentox

Sentox VX-1, or simply Sentox, was a nerve gas developed by Omicron International for the Department of Defense. A group of terrorists known as the Dawn Brigade working for Vladimir Bierko were sold the gas by White House Chief of Staff Walt Cummings, who was a pawn in a larger conspiracy directed by James Nathanson, Christopher Henderson, President Charles Logan, and a group of secretive businessmen led by a man named Graem (later revealed as Jack's brother in Day 6). Sentox was the primary threat during Day 5

Sunrise Hills Shopping Mall attack
Dawn Brigade terrorists Polakov and Komar partially deployed a single canister of Sentox into the ventilation system of the Sunrise Hills Shopping Mall, killing 11 people. Jack Bauer, who was at the time undercover with the alias Jacob Rossler, managed to stop the flow of nerve gas, killed Komar, and closed down the ventilation system. While pursuing the escaping terrorist, Jack rescued a small girl. Polakov remained under surveillance, and CTU followed him back to a repair garage owned by a civilian where Polakov's superior, Ivan Erwich, was operating. Erwich observed from a distance the arrival of the TAC team, ordered Polakov to kill himself, and then fled.

Tyler Memorial Hospital attack
Vladimir Bierko, now directing the Dawn Brigade's activity, sent Viktor Grigorin to deploy a single canister of Sentox near a ventilation system inlet. However, Curtis Manning and a TAC team intercepted and killed Viktor, and secured the canister in a containment unit seconds before the gas was released. This attack was actually a diversion, and it allowed Bierko time to attack his next, primary target.

CTU Los Angeles attack


Bierko's operative named Ostroff deployed a single canister of Sentox in CTU LA's ventilation system using Lynn McGill's keycard, sold to him for $20,000 by Dwayne Thompkins (whom Ostroff later killed, along with his girlfriend, and Lynn McGill's sister, Jenny. Jack killed Ostroff, but not quickly enough to locate and secure the canister. However, Jack found the timing relay switch and PDA, and after reporting the danger, Bill Buchanan ordered an evacuation (Code 6) and asked Chloe O'Brian which rooms they could seal off from the gas. After being informed of the locations (the Upper Offices, Situation Room, Holding Room 4 and Clinic Isolation), the remaining workers and visitors scrambled to the Situation Room, Bill Buchanan went to the CTU Director's Office, Lynn McGill & Harry Swinton remained in Holding Room 4, and Tony Almeida, Agent Burke and Christopher Henderson were in Clinic Isolation. After these rooms had been sealed, a female CTU worker asked to be let into the Situation Room, but was refused entry by Jack because of the danger to those the Situation Room; she died as they watched helplessly. After this, Edgar Stiles came running out to the Bullpen. From inside, Chloe heard him say her name; it was his last word. He too died in front of the agents in the room. (He received a silent clock for his death.)

Wilshire Gas Company attack


Vladimir Bierko, Mikhail and a team of 5 others infiltrated Wilshire Gas Company and deployed 16 canisters of Sentox in the main distribution tank. When Jack, Curtis, and 2 other CTU field agents stormed the gas plant, they killed all of Bierko's men, captured him, and incinerated the Sentox by igniting the natural gas it had to mix with to deploy. Only minimal, harmless traces were found in the pipes leading away from the plant.

The Natalia attack


Vladimir Bierko and his last team infiltrated the Russian submarine Natalia, and deployed a single canister of Sentox near the entrace of the submarine and killed all but one of the crewmen, in an attempt to access and use the sub's Scorpion Land Attack missiles and use them against civilian targets. Jack Bauer, Christopher Henderson, and Agent McCullough infiltrated the submarine after the gas had been neutralised, secured the missiles and killed all of the terrorists, including Bierko himself.