JACK 'Are you out of your fucking mind?'
WENDY 'No. It's the truth! Really. I swear it. Danny told me. He went up into one of the bedrooms. The door was open, and he saw this crazy woman in the bathtub. She tried to strangle him!'
JACK 'Which room was it?'

Jack is being lured to the Hotel's one-sided portal Danny initiated by TURNING the locked knob. He has just been conversing with 'someone else' in the hotel, but accuses Wendy of being out of her mind for suggesting Danny saw the exact same thing.