The first hour of this two-parter deal with the plot to kill Hassan.
After CTU decoded the encrypted message on Meredith Reed's hard drive, they saw schematics of a bomb. It looked like it was set under the UN, so Hastings ordered an evacuation of the building. While this was going on, Jack was getting beat up by a police officer that thought he was responsible for the double homicide of the couple that was held hostage last week by the evil Russian dude posing as a cop.
One officer came to his sense, though, got his partner away from Jack and followed through on Jack's advice to find out where the deceased cop was meant to be stationed that night. The answer, of course, was as part of Hassan's protection. Away Jack and this officer went... to the UN!
On his way, Jack called Ortiz and explained the situation. Cole had to make an immediate decision and did so: he spent to the front of the caravan and turned into Hassan's vehicle just as the evil Russian dude set off an explosive under the street. Both cars blown up, but everyone inside was okay.
As Hassan was rushed over to CTU, his wife and daughter remained in a car with Farhad. He then actually dialed up the killer, who had been followed into a building by Ortiz. The killer told Farhad everyone would likely connect him to the plot soon. As a result, in a bit of a stretch, Farhad got out of the vehicle, killed a CTU agent and fled the scene.
Jack eventually saved Ortiz from the evil Russan dude, but made the mistake of killing him before they could interrogate him. He did, at least, take pictures with his phone of the guy's tattoos. These will soon come in handy.
(** In B storyline news: the guy stalking Dana showed up and said he's out her former identity if she didn't let him stay at her apartment. She agreed to do so, supposedly for one night only.)
Over at CTU, Hastings let Reed go because she had clearly been set up. When she spoke privately to Hassan, he ended any relationship between the pair because he finally realized the damage it could do to his plans for peace.
Also, Farhad's motivation came into focus: weapons-enriched uranium was found on the body of the dead Russian dude. This means he recently came into contact with it. How could that be? Hassan knew: Farhad always said their country had to possess nuclear power in order to compete with the West. There were even Russians offering up uranium rods a few years ago, though Hassan turned them down.
Now, it's clear Farhad is working with them. Viewers then saw this for ourselves, as he escaped to a meeting with an older Russian guy that claims to possess the rods and has arranged a deal for them with Farhad.
But CTU wants in on that deal! It's called in an agent that used to work as an undercover spy with the Russians: Renee Walker! We're asked to somehow believe she was undercover with the Russian mob for two years, as Renee is flown in to headquarters. Once there, we see how traumatized she's become. She's clearly depressed (we later learn she attempted suicide) and she lost her job with the FBI after almost killing a suspect during interrogation.
Jack doesn't think she's ready to go back undercover as Hatings suggests (in order to infiltrate the mob and set up a competing buy), so he says he'll accompany her and be the buyer. Hastings is all for it, though Renee doesn't want the company. The reunited pair go off to meet a source that will hopefully connect them to a higher-up guy (named Vladimir) in the mob that has the rods.
With Jack listening from the car, Renee sweet talks a Russian guy with a police monitor on his wrist. She wants him to take her to Vladimir and says she can help him escape the cops by cutting off that monitor. She places his hand in a vice -- and cuts off the hand!
Jack runs in, aghast, and asks what the Hell she is doing. He says this mission is over. Renee's response? She's just getting started!