Humans has already gone global - but series two of the Channel 4 hit is about to get even bigger.

Sonya Cassidy - who plays Hester, a new sentient Synth - told Digital Spy that the ambition of the next seven episodes is "incredible".

"The scope of the show - for Hester and for all of these characters, and with everything that is coming up... the second series just got broader and broader as the show went on," she said.

"I think it's quite incredible what we've been able to fit into eight episodes. I think the fans are in for a treat."

Cassidy was tight-lipped about what's in store for Hester, but did hint that she might be driven to extreme acts after being mistreated and hunted by human beings.

"How would you expect someone, that is effectively still a child, to perceive this new world, given those experiences? One of her first experiences is being lied to, hunted and shot at and she's having to survive and adapt in the only way that she knows how.

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"There are things she does that are completely logical... and then there are other things that might possibly very questionable!"

Sonya Cassidy as Hester in 'Humans' series 2pinterest
Colin Hutton / Channel 4

Humans kicked off its second series last Sunday on Channel 4, with fugitive Niska (Emily Berrington) handing herself over to the Hawkins family.

Having killed a human, Niska is willing to face justice, but demands to be tried as a human - so could the show be about to tackle Synth civil rights?

Cassidy told us that, for all the show's sci-fi trappings, there are definitely parallels between what we'll see in Humans and events in the real world.

"I love that it's set in a parallel present that all of us, whether you're into sci-fi or not, can relate to - and think about these issues that are brought up in the show.

Sonya Cassidy, Colin Morgan and Ivanno Jeremiah in 'Humans' series 2pinterest
Colin Hutton / Channel 4

"[It explores] the way we treat other people that we deem second-class citizens. We're seeing it all over the world: we've been seeing it throughout human history, but what's especially shocking is that it's still so prevalent now.

"What I think's great about Humans is it doesn't patronise, it's not spoon-feeding you with that, it simply poses those questions and forces us to think about those parallels."

Sonya Cassidy stars in Humans, continuing this Sunday at 9pm on Channel 4.

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