Protecting "Sweeney Todd" and the notebook
We are of course not 100% certain that the therapist's patient is Sweeney Todd. However, if he turns out to indeed be the Demon Barber of Fleet Street, which I'm sure you'll agree is a Name To Run Away From Really Fast, then I think we're taking the wrong approach.
We are trying to protect several people, most notably the therapist, from getting in danger. What we are forgetting though, is that "Sweeney" is a fictite as well, albeit, unlike the others, a Villain Protagonist. This means he has to be kept out of danger himself, or we might not be able to send him back. Since we are not able to contact him (he may have fled and may be on the run), I think we should put Holmes and Poirot on the case. They may be able to track him down if they join forces.
And about the notebook: Although I'm sure it will reveal a lot about the patient, I think "Sweeney" is using a fake name, so we won't find his name in the notebook.
Also, as you may have noticed, I'm new here, and I hope I'm not sounding like a Know-Nothing Know-It-All, but these are just my thoughts on this case
We are trying to protect several people, most notably the therapist, from getting in danger. What we are forgetting though, is that "Sweeney" is a fictite as well, albeit, unlike the others, a Villain Protagonist. This means he has to be kept out of danger himself, or we might not be able to send him back. Since we are not able to contact him (he may have fled and may be on the run), I think we should put Holmes and Poirot on the case. They may be able to track him down if they join forces.
And about the notebook: Although I'm sure it will reveal a lot about the patient, I think "Sweeney" is using a fake name, so we won't find his name in the notebook.
Also, as you may have noticed, I'm new here, and I hope I'm not sounding like a Know-Nothing Know-It-All, but these are just my thoughts on this case