The actor, who plays Will, told E! Online that everyone working on the show is "really excited" about the new episodes.
Charles said: "We're bringing in everything from where we left off last year.
"I think it set everything in motion for the third season to get really complicated and twisted and so far the writers have been delivering all of that."
Charles also teased that viewers will find out more about Will, saying: "In the next episode [we film] we're going to start digging into Will's past a little bit, so I'm excited about that."
Charles's co-star Alan Cumming has already revealed that fans will get to know his character Eli a little better in the third season, which premieres on Sunday at 9/8c on CBS.
> Michael J Fox returning to The Good Wife for third season
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Watch a trailer for the third season of The Good Wife below: