Cheng Zhi was Head of Security at the Chinese consulate in Los Angeles. When Consul Koo Yin was killed during a raid on the consulate, Cheng was appointed by Deputy Consul Su Ming to lead the investigation. Cheng eventually learned from Howard Bern that Jack Bauer was behind the attack on the consulate and captured him at the end of Day 5. He was responsible for the torture of both Bauer and Audrey Raines. His acquisition of the Russian FB subcircuit board sparked an international incident between the United States and Russia.

During the events of Day 4, Habib Marwan planned on using a nuclear warhead against the American people. When CTU learned that Lee Jong could help capture Marwan, he hid at the Chinese consulate. The Chinese government agreed to cooperate, but not in the appropriate time frame. President David Palmer authorized for Jack Bauer to run an covert operation in order to get Jong into custody. During the operation, Chinese guards fired and accidentally shot and killed Consul Koo Yin. Yin's successor, Su Ming, was convinced the US government was behind it.

Cheng confronts Bill Buchanan at CTU. ("Day 4: 3:00am-4:00am")

Added by Unbreakable1000As head of security at the consulate, Cheng Zhi investigated the death of the consul and he wanted someone to be brought to justice for Yin's death. When Cheng looked through security cameras, he noticed one of the Chinese guards managed to pull the mask off one of the agents. Cheng was able to run the face of the agent and he discovered that it was the face of Howard Bern, a field agent with CTU Los Angeles. Cheng headed over to the Los Angeles office, in order to question them about the raiding of the consulate.

Cheng arrived at CTU and spoke with Bill Buchanan, the Regional Director of CTU. Buchanan was able to fake hourly reports, that proved that Jack Bauer and his team were at CTU during the raid. When Cheng confronted Audrey Raines, the Senior Policy Analyst of Secretary of Defense James Heller, she confirmed that she was with Jack Bauer during the midst of the operation. When Cheng asked about Howard Bern, CTU was able to prove he was at a different domestic office and Jack helped Bern escape from the building. After speaking with Edgar Stiles, Cheng realized he wouldn't be able to implicate the government and that Bauer was behind the attack.

Bern tried to get out of the city, Cheng and his men were able to find his location. They illegally abducted him and pulled him in a van. Cheng interrogated Bern and told him he would let him go if he told him who ran the operation. Bern eventually confessed that Jack Bauer was the one who ran the operation. Cheng contacted the US government and told President Charles Logan that the Chinese government would put aside the involvement of the US government if Bauer was given to them and prosecuted under Chinese laws.

With no other choice, Logan agreed to Cheng's terms and told him a Secret Service agent would deliver Bauer to the Chinese. Logan's Chief of Staff, Walt Cummings, was convinced Bauer would give up National Security information. He sent Dale Spalding to apprehend Bauer and kill him. When Bauer attempted to escape from CTU, he faked his own death to make it look as though he was shot and killed by Spalding. Cheng and the Chinese government did not go forward with accusing Logan's administration of being involved in the covert operation.