After a nuclear disaster caused by several terrorist attacks wipes out most of North America, residents of a small Kansas town have to come to terms with a very different reality.

The fallout from the nuclear blast in Denver will hit Jericho in an hour and Jake has to get the residents inside. The official shelter is not adequate and Jake must find another shelter to protect them. Emily faces troubles of her own while being picked up by who she thinks are two officers.

After seeing a broadcast via satellite from Asia, Jake gathers a group of people together for information gathering. After finding out that there is information out there, Jake suggests having four search parties to go out to get a better understanding what is going on outside of Jericho. The search parties set off in four different directions.

Jake finds a stranger who is sick with radiation poisoning and he must make a decision whether or not to help him. The hospital’s generator is running out of gas and the residents find that their supplies are also running low.

The children of Jericho start to return back to school. A power line that has fallen causes an accident on the playground when the power returns. Jake has an argument with his mother regarding a secret that Jake hasn't disclosed to his dad.

Hawkins must step in when an argument between Jake and an adversary becomes heated. After an electromagnetic pulse leaves Jericho in the dark crime runs rampant. Later, Jake is held at gunpoint and is rescued.

The slick gang leader Jonah bails Mitchell out of jail and agrees to give back the food that his bandits stole and agrees to keep out of Jericho. This plan strays off-course as Jonah negotiates new terms involving Jake and Emily.

Supplies are dropped by air into Jericho and the Green's and Hawkins think that they know where they came from. Jonah Prowse returns to Jericho causing even more trouble.

Some of the residents of Jericho are concerned that Gray's actions may actually make Gray the new mayor. In other news, Mitchell claims that Jonah is the killer under much speculation.