Catching Fire is the aftermath of the Games and, as a victor, Katniss gets to tour in all the districts. But by doing so, the rebellion that was already stirring becomes a reality - and Katniss get blamed for it, obviously. And, cherry on the cake, the 75th Games take place that year, and every 25 years... something special is planned.
The first book was in my opinion quite good, and the second keeps delivering - it's also quite good. The secondary characters (or maybe tertiary, at that point?) are maybe a bit more confusing, but apart from that, I liked it as much as the first one. The end is kind of shocking, and gives a good feeling about the third one.