Lost tv series, the clock chapter?

Hi guys,
just wondering if anyone has a good knowledge about the Tv serie called lost;
i started to watch the series while ago and i can t remember the name of the last episode that i watched so maybe some of you could help me if i give you some information regarding this.

I remember clearly that i was watching the cast of Lost when they discovered the underground apartment with a clock and every time someone had to push the red botton to avoid the zeros .

Because i wanted to rent the dvd i don t have a clue which one it is so if anyone has any idea i would really appreciate it

Thanks a lot