The plot is simple. The USA has been hit by a zombie outbreak and is overrun by the living dead. Your only hope is to make a beeline to Canada. You got your trusty car (until it runs out of fuel or gets damaged) and some simple weapons at the start of your journey. On the way you will run into friendly and not so friendly parties, let alone a lot of zombies that want to tear you limb from limb.
The game is an action game where you control one member of a group of up to four. You can switch which member you control and the others are left to the AI. Between fights there are stretches of road where you get info on the group and some insight into their minds. Every now and then there are decisions to make, such as taking someone into your team, helping someone, fighting bandits, and so on.
There is quite a bit of emphasis on item management as well as thinking about which weapon to use. Some stronger weapons like the sledgehammer might deal more damage but have longer recovery, etc.