This video probably sums up the episode, if not shows an important element of the plot; singer Danielle Marsh (portrayed by Helen Reddy) is on a tour to New York and moves in with Dr. Mark Sloan (portrayed by Dick Van Dyke) because Marsh has a grand piano in which she claims calms her nerves. During rehearsals, she began to feel agitated and disturbed, partly because of a man stalking her which she had met earlier in New York, and that she might bouts of paranoia/delusions... and then the investigation and treatment begins so that it does not affect Marsh's upcoming concert

I'm not posting the full episode because that would subvert and nullify the nature of this video being fair use. I believe it's now on Paramount Plus which you can watch the full thing (legally)

Original transmission: 4 May 2000
Season: 7
Episode: 22