From the publisher's website :-
You’d thought you’d seen the worst of it - until the entire party plummeted to the lower lairs; a series of caverns that are deeper, darker and more dangerous than any you’ve yet known. But it’s the danger from within that you must concern yourself with now. To see daylight again, you will need to use every skill and ability at your disposal. Remember... Without teamwork, you will never survive. Without betrayal, you’ll never win.
Welcome Back to Cutthroat Caverns.
Okay, that's what it says on the box... what's it really like?
Deeper & Darker is the first expansion to Cutthroat Caverns and further extends replay value with 15 new Encounters. Like in the core set, these Encounters all have a very different feel and require new strategies to overcome - both as a group and as an individual. As is implied by the title, these new critters are more challenging than ever and will put your party to the test. You may find yourself playing backwards in time against PARADOX, be tempted one too many times by ASHTONGUE THE CRUEL, or find that seven heads are not better than one with the HYDRA. Plus, we've anticipated the desire to make the characters in the game more dimensional. So we've built a whole new 'character enhancing' game mechanic, one-use special abilities that are unique to each character and suited to their race or class specialties. With special abilities like Blackclaw's Fury, Ranged Salvo and Fleece you may find the tools you need to give you the edge.
THIS IS NOT A COMPLETE GAME. YOU WILL NEED A COPY OF THE CORE GAME TO PLAY!