In scenes which air later this week, India will be murdered by sinister new character Cameron after an experiment with online dating goes horribly wrong.
Strait-laced India (Beth Kingston) makes the terrible decision to meet Cameron alone after Texas (Bianca Hendrickse-Spendlove) brands her boring, which encourages her to take a risk for once. Show bosses have said that they want the storyline to promote the importance of online safety.
In an interview with the official Hollyoaks website, Marquess explained: "It's also about grief, this story, and clearly for Texas who is quite a new character in the show - she's been in it about six months now - she's been quite light and quite daft so it's interesting to see her cope.
"She feels responsible - she's not, but she feels responsible for what's happened to India. And it is about dealing with really, really strong emotions when you're relatively young. So I think the online safety will run all the way through it, but actually it's a bigger story than that.
"It's about how you cope with feeling responsible and what it's like to lose somebody who's really, really close to you. And the real tragedy for Texas is that because she was always taking the mickey out of India, she never really got to say how much she loved her - so it's really sad."
Asked how the idea for the plot came about, Marquess replied: "It came from one of our writers. There's a twist in it, as the viewers will see, about who the killer is. And I loved that idea straight away."
Marquess has previously confirmed that Cameron - played by Jeff Rawle - will be a dangerous presence in the village "throughout 2011".