As "Gotham" gears up for its third season this fall, star Ben McKenzie promises a Jim Gordon like you've never seen before -- one who's nearly at rock bottom.

Joining journalists for a behind-the-scenes chat at Comic-Con International in San Diego, McKenzie explained how Gordon's at the start of a long, downward spiral, one that Leslie Thompkins (Morena Baccarin) and Harvey Bullock (Donal Logue) may not be able to pull him out of.

What kind of emotional state do you find Jim Gordon in at the beginning of the season?

Ben McKenzie: Not a good one. He left Season 2 cleansed in a way by Hugo Strange's psychological deconstruction of him, and he went off to find Lee. We start Season 3 with him finding her but, as with most things in Gotham, it doesn't go well. So he feels at sea.

We move forward in time about six months, and he's back in Gotham, and the monsters that were unleashed at the end of Season 2 are now running amok, and Gordon is a bounty hunter. Gordon is no longer with the GCPD. He is chasing these monsters down for a price, and collecting that money. He's sort of disillusioned with the whole thing.

Has he completely given up on the law? As a bounty hunter, is he taking matters into his own hands a little more?

He is, yeah. He's certainly not a villain. He certainly doesn't inflict pain just to inflict it. He has a certain morality, but it's far, far away from where found him initially. He's learning a lot of things, and with each lesson he learns, he takes a step forward, but he also in some ways falls apart a bit.

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We will eventually see a Gordon who struggles at times to keep it together because of how rough Gotham is and because how few allies he really has. And the subtitle of the season, "Heroes Will Fall," is indicative of what thematically we're doing in the season with, not just Bruce Wayne and the other heroes, but with Gordon himself. He will fall a long, long way and have to pick himself up again.

What's his relationship like with Bruce Wayne this season?

Well, as we start the season, Bruce is really on his own journey, and Gordon is on his own. Their paths will merge later on, and they've sort of reset their relationship a bit. Gordon doesn't feel as much a responsibility to Bruce to figure out his parents' killer, because it seems to all, not have been tied up, but effectively Indian Hill was the breeding ground for a lot of this stuff, and that had a lot to do with what ultimately manifested in Bruce's parents' murder. But the Court of Owls is really behind the whole thing, and that's where we'll get to in season three. That's really the force that's behind everything.

Was it exciting to have Morena Baccarin finally back in the mix?

Yeah, I saw her occasionally [off set]! [Laughs] Yeah, it was, and it's different. It's different, yeah, and it's wonderful to play that. It's giving us a brand new dynamic to play, which is a lot of fun. There's a new love interest for me in Valerie Vale - I think I can say that that's a love interest. I don't think it's much of a surprise. It's professional, and then not. And [Lee] has a new man as well. So we get to have fun with the kind of love triangle aspect.

How are things between Jim and Harvey Bullock?

Harvey's his one conduit to sanity. He's the one person sort of reminding him that ... Harvey's been in some pretty dark places in his life, too. He's pretty happy sometimes to sort of drift in those places. But even he looks at Jim and says, "Hey man, you've got to pull it together."

So I think Harvey's kind of always mentoring Jim and always there for him. Absolutely, at the end of the day, Harvey's a grounding force for Jim, and someone who keeps him from falling over into the abyss.

"Gotham" returns Monday, Sept. 19, on Fox.