Adam let's things play out.

Against his better judgement, Adam didn't stop Susannah. He could have sworn he had died and gone to heaven. Not only did he find his girlfriend's mum insanely attractive, he was also in ecstasy of the taboo nature of the contact.

"I've wanted you since the first day I met you, Adam," Susannah said softly. "I know it's risky and I'm betraying my daughter, but I want you. I can't even count the times I've fantasised about you."

Without another word, as Susannah locked eyes with Adam, she slowly slid the flies of his jeans down and reached inside. With ease, she pulled Adam's now raging hard dick from his boxers and worked it with her fingers. Adam's heart raced at the sight of his girlfriend's mother giving him a hand job.

"What a nice cock!" Susannah purred as she quickened her pace.

"Thanks," Adam said with a grunt. He was starting to lose himself in the pleasure he was experiencing and forgetting any risk of Helen coming downstairs. Adam couldn't believe how long she was taking but hoped she'd take as long as it took him to cum.

"Are you really just letting me toss you off, with my daughter, your girlfriend, upstairs?" Susannah said, suddenly stopping and squeezing Adam's balls more firmly than he liked.

Adam knew it was too good to be true, it was a trap! But wait, what would Susannah get out of proving her daughter's boyfriend was so easily led by his lust he'd let her jerk him off with very little resistance. Slowly the cogs whirred and things finally clicked into place. If he played his cards right he might just get out of this on top. Helen had been upstairs far too long to just be looking for the book, and they had just left it on the desk. He didn't know whether to be angry or impressed by her moxie.

"Helen, I've known it was you from pretty much the start," Adam said trying to sound as confident as he could.

"Really?!" came Susannah's voice in a tone that was remarkably like Helen's when she was caught by surprise. "Well I suppose I should be pleased you weren't willing to let my mum do all this to you. What gave me away?"

"Oh, well, I suppose it was the way you weren't exactly speaking the same way she normally speaks," Adam said meekly.

"For fucks sake, I can never get one over you!" Helen whined releasing Adam's balls from her grip. "I don't really know what I was planning to do to be honest. I suppose I was angry you'd almost given away the reality of the book when I wanted it to remain our secret. And the thought of taking over my mum's body to tease you was too good a temptation to resist. The rush I felt when I entered her! And then the power I felt over you as a sexy older woman."

"Wait a minute, when you were in my body I could feel and see everything you were doing. What the-"

"It's fine," Helen said cutting her boyfriend off and gently patting his leg. "I found a way to send my mum's mind to sleep whilst I'm inside her body. That's why I was taking so long. You really think I want to try and explain this to her?" Susannah said gesturing to Adam's now semi-erect penis. "Though there was a passage that suggested I could make 'the host' believe they were responsible for every action," Helen added with a mischievous grin.

"You'd really like your mum to believe she wanted to toss me off and went through with it?"

"Pah, you're right," Helen pouted, crossing her arms beneath her chest.

"But seeing as she won't remember a thing, maybe you should finish what you started?" Adam said shaking some life back into his deflating member.