I just started listening to it myself but here it is:

The world has been destroyed by radiations and the survivors lived in bunkers for hundreds of years.

One day a group of people living in a bunker receives a visit from outsiders, they're a team from another colony that seek "something" from deep in the mountains, they seek help to retrieve it together with the bunkers and two people get selected to go in an expedition with a time limit of one week.

That's the gist of the first episode, hope you like it! 😎👍