Hollyoaks schemer Sienna Blake will start a small fire at The Dog in the Pond in a twisted scheme against her friend Nancy Osborne.
Sienna embarks on the dangerous plan as she wants Nancy's husband Darren to see that his partner's painkiller addiction is making her an unfit mother.
Anna Passey, who plays Sienna, told All About Soap: "She wants to teach Nancy a lesson. You see, Nancy's not listened, lots of people have tried to help her, and now Sienna needs to shock her and make Darren see how serious this is.
"Sienna finds Nancy passed out on the sofa. The iron is there and there's a pile of ironing on the side, so Sienna puts the iron hot-side-down on Oscar's clothes. She thinks she'll start a fire and it will draw attention to how far things have gone with Nancy, and open Darren's eyes to what a bad mum she is."
What Sienna doesn't realise is that baby Oscar is asleep upstairs at the pub, and her shocking actions have put him in danger.
When Darren (Ashley Taylor Dawson) discovers the blaze and raises the alarm over Oscar, a frantic Sienna rushes upstairs to rescue the youngster and is hailed a hero.
Nancy (Jessica Fox), meanwhile, faces a backlash as she is blamed for the fire. Things then get even worse for her as she discovers that her mum has had a fatal car accident in Canada.
Passey added: "After lots of arguments, Nancy discover that her mum's been killed, so she has to go to Canada. She asks Sienna to stay and look after Darren and Oscar - she's inviting the wolf into her home!"
With Sienna wanting a place in the Osborne clan due to her own troubled family history, it's clear that this may only be the beginning of her scheming.