With its most recent episode, “Casey Casden,” the US version of Shameless has found its own authentic voice, blasting its way out of the shadow of the UK version, to which it had been staying remarkably true. The storylines are still for the most part the same, but there are minor, subtle variations, a set of low-key differences that have accumulated and evolved into a unique, stand-alone personality.

The Chicago setting is great: rough, raw, uncompromising in a much tougher and larger way than the original Manchester setting (sorry, Manchester!). When the cops come out with choppers and SWAT teams, it’s just more convincing here.

But that’s not what makes this version, that’s not what really makes it tick.

It’s Emmy Rossum that gives the show its wild heart and lonely soul; her feral beauty strikes at you, demands you notice it. This is the role she was born to play. The character of Fiona is key to the entire show, just as she was in the UK: in this remake, Rossum ups the ante and drags every scene out from under her costars, whoever they are, however brilliant and magnetic, charismatic or compelling they may be — doesn’t matter, because Rossum is providing the soul that Shameless is utterly dependent on. It is a wild ride, chaotic, unruly, beautifully so, but it needs this soul for you to buy into its unhinged brilliance.

Episode 4 was the one that turned the corner, when the show began to hold its own in the face of Rossum’s raw and heartbreaking truth. The storylines had punch and accereleration, and they ratcheted together to move forward hard and fast, deftly and solidly. The family was drawn into the scheme to return a toddler that youngest daughter Debbie had, inadvertently, stolen. Elsewhere, Lip and Ian were trying to steal a water heater, and neighbor Kev was trying to work out how an off-hand comment had led to the quickly-spreading wildfire news of his apparent engagement to Veronica. It was tightly scripted chaos, making its way through the complex character work and reverse heist plotting with ease.

All the storytelling elements dovetailed in just the right way, and suddenly, wonderfully, we saw the true power of the ensemble. Not just the actors, but the writing (by Cindy Caponera), directing (Todd Holland), producing and soundtrack song choices. With this episode, Shameless exploded into life, exceeding the promise of the pilot and the fascinating and entertaining second and third episodes. It came into its own, setting up a more assured trajectory for the remainder of the season.