well, i'm not gonna say much, but if u intend 2 watch it start with season 1 2 and so on. its about an agency that is called counter terrorist unit or "CTU" for short.this agency's responsibility is to deal with any threat to the USA. the amazing thing about it is that every season deals with one day with all its events which gives the chance or amazing details to be added and those writers know what they're doing. to be brief, it wouldn't continue for six years{so far} if it wasn't that good,it wouldn't also be nominated to so much awards and getting a great deal of them, so without going into details, if u didn't watch it till now, u are missing something that can and will change your life.