In a logline less words to say basically the same thing is better.
—–
“When a narcissistic doctor begins to get stalked”
“When a narcissistic doctor is stalked”
—–
“by a revengeful, criminal and psychotic patient who is dying because of a medical mistake she made when treating his disease,”
“by a psychotic patient who’s dying because of a medical mistake,”
—–
—–
The final line needs to be more specific. Because we cut the earlier part down you can add a little bit here:

“she must protect herself and her family.”
“She must (Be more specific about what she must do, how does she protect her family???) if her and her family are to survive.”

Hope that helped, good luck with this!

Great points Nir. A couple more points along the lines of how this is worded.

‘accidentally makes a horrific discovery’ could be shortened to, ‘makes a horrific discovery’ there is no need for accidentally.

Also, there doesn’t seem to be any reason to tell us she is stealing the wallet. It adds nothing, it;s the discovery that’s important, not what she was doing when she discovers it.

Finally. ‘the couple is not alone in a shabby room of a love hotel.’ Tells us nothing. Many times kinky people will have someone hiding in the closet watching the sex act. I don’t see how this would be ‘horrific’ to a hooker.

On the other hand, If it’s a ‘killer’ in the room then say that instead. Then as DPG stated, tell us what she must do.