Logan wrestles with his conscience when he learns that Martha is riding in the motorcade with the Suvarovs.

Audrey convinces Curtis to take action as Lynn continues to abuse his authority.

Jack learns that an ex CTU agent, Christopher Henderson, works for a company which is connected with the nerve gas.

Jack interrogates Henderson's wife about her husband's connection to the terrorists.

Lynn begs his sister to return his stolen keycard, while Tony regains consciousness and learns of Michelle's fate.

Martha gives Logan the cold shoulder, while Curtis tracks another nerve gas attack to a local hospital.

Jack takes Henderson to CTU for questioning. Once there, he faces an unhappy reunion with his daughter, Kim.

Mike appeals to Martha for help as Logan faces pressure from his Vice-President to declare martial law on L.A.

Lynn connects the theft of his keycard to an impending strike on CTU, but his warning comes too late to stop a terrorist from infiltrating the building.

Jack and Lynn must take action when they discover that the nerve gas is breaking through the protective seals that are keeping the CTU survivors alive.

Chloe wrestles with her grief over Edgar's death, while Tony contemplates revenge against Henderson.

Martha bolster's Logan's spirit as he wavers under more political pressure from Gardner.

Jack pushes Audrey for answers when evidence indicates that she may be involved with the terrorists.

Wayne and Aaron flee from a group of gunmen who have orders from Henderson to kill them.

Bierko and his men gain access to a natural gas plant, where they plan to distribute the nerve gas throughout L.A.

Jack and Wayne locate a source inside Logan's administration who has information on Palmer's assassination. But things get complicated when they learn that Henderson is using leverage to keep her silent.

Audrey is forced to choose between Chloe and Buchanan as Homeland Security begins to absorb CTU.

Jack and Wayne locate a recording that definitively proves Logan's involvement in the terrorist conspiracy, but Henderson corners them in the hopes of destroying the incriminating tape.

Logan tries to cover his tracks by issuing a warrant for Jack's arrest.

Audrey contacts her father for help, while Chloe gives her cover while helping Jack evade CTU.

Jack shows Heller the incriminating recording in the hopes that he will help them take down Logan, but Heller has plans of his own that will save face for the presidency. Miles tricks Chloe into leading CTU to Jack and Audrey. Mike and Martha both become more suspicious of Logan's actions, while Heller confronts the president with an ultimatum.

Jack captures Henderson and attempts to force him to hand over the recording, but Henderson targets Heller to buy himself more time. Logan confesses his involvement in Palmer's assassination to a distraught Martha. Miles traces Chloe to Buchanan's home, but Hayes finds herself questioning Logan's motives as CTU closes in.

Bierko escapes from the transport taking him to Division and uses his last canister of nerve gas for a surprise strike. Jack is forced to work with Henderson to find Bierko, but Henderson wants something in return. Logan takes drastic steps to deal with Aaron when he won't go along with the cover-up.

Jack and Henderson wage an assault on the submarine as Bierko prepares to launch an attack against L.A. Chloe brings in someone from her past to aid her. Martha and Aaron enlist Mike's help in their plans to expose Logan.