Carl Webster (Jonathan Howard) is known for being one of Coronation Streets’ most ruthless characters.

You can’t really have a full blown affair with your brothers wife (while also sleeping with their neighbour), be a big cog in a car-theft racket and threaten your nemesis’ elderly father without a serious dark side.

But Carl plummets to new depths next week, when he manipulates his dementia-suffering sister, Debbie Webster (Sue Devaney), convincing her that the evidence she’s found that points to his affair with brother is nothing more than circumstantial, and her illness is making her react so strongly.

We know. We’re angry, too.

Last week saw Abi Webster (Sally Carman-Duttine) finally call an end to her marriage with Kevin Webster (Michael Le Vell) after months of being locked in a sordid affair with Carl.

Though Abi initially tried to resist temptation, upon learning that Kevin was lying about needing further cancer treatment, himself concerned about his wife’s growing closeness to his brother, she fully gave in and her and Carl have been hooking up as often as they’ve been able, primarily at Carl’s base in the Chariot Square hotel (remember that bit).

Though they were caught by Weatherfield’s most toxic resident, Tracy Barlow (Kate Ford) and extorted for cash, Carl dealt with her by having her shop destroyed and threatening her dad, Corrie icon Ken Barlow (William Roache).

Upon learning that Kevin’s cancer was still in remission and hearing him wax lyrical about his plans for their future, Abi could take no more and told Kevin that their marriage was over…stopping just short of revealing that she’d moved on with his brother.

Though still playing happy families for now, Abi is rattled next week when Debbie spots her with a hotel key…a key from the hotel she owns. The one that Carl has been staying in. The one I told you to remember earlier?

Heading to the garage with Debbie hot on her trail, Abi tries to reason that the key was from a previous stay and she’d simply forgot to hand it back. Debbie isn’t convinced as Abi splutters and stutters her way through excuses.

Enter Carl. In perhaps his cruellest move yet, he uses Debbie’s dementia against her, convincing her that it’s her illness making her forget about Abi’s previous hotel stay. Even Abi herself is horrified at his actions.

Will Debbie eventually see through her brother? And how will she feel when she realises what he’s done to her?