Vacation with your Wife and her Stepsister

Your marriage isn't perfect- who's is- but you still have a great time with your Wife.

When her Stepsister is around, however, she seems to corrupt and change your lady.

The lady pushes her to be more domineering and expecting more from you than usual.
You don't look forward to her trips.

For the Summer, you book a nice Cabin in the Woods for just you and her to enjoy.

Fate intervenes, however, as the Stepsister is newly divorced and 'can't be left alone right now.'
Joy.

The whole trip there is as bad as you imagined it would be, with Emily egging her on the whole time.

Your Wife can be a bit kinky when you are alone, so you packed some bondage gear based on the original plans.
You've had some fun with that...

As Emily keep talking, you think about how good it would be to gag her- really shut her up!

The wheels start to turn...

You three will be alone.
You have the supplies.

Do you have the willpower to go through with it?