Commentaire Littéraire The Hound of the Baskervilles (Sherlock Holmes)

Sujet du devoir

Voici l'extrait à commenter (chapitre 9): 

I hurried along the road ot the top of my speed without seeing anything of Sir Henry, until came to the points where the moor path branches off. There, fearing that perhaps I had come in the wrong direction after all, I mounted a hill from which I could command a view--the same hill which is cut into the dark quarry. Thence I saw him at once. He was on the moor path about a quarter of a mile off, and a lady was by his side who could only be Miss Stapleton. It was clear that there was already an understanding between them and that they had met by appointment. They were walking slowly along in deep conversation, and I saw her making quick little movements of her hands as if she were very earnest in what she was saying, while he listened intently, and once or twice shook his head in strong dissent. I stood among the rocks watching them, very much puzzled as to what I should do next. To follow them and break into their intimate conversation seemed to be an outrage, and yet my clear duty was never for an instant to let him out of my sight. To act the spy upon a friend was a hateful task. Still, I could see no better course than to observe him from the hill, and to clear my conscience by confessing to him afterwards what I had done. It is true that if any sudden danger had threatened him I was too far away to be of use, and yet I am sure that you will agree with me that the position
was very difficult, and that there was nothing more which I could do. 

Our friend, Sir Henry, and the lady had halted on the path and were standing deeply absorbed in their conversation, when I was suddenly aware that I was not the only witness of their interview. A wisp of green floating in the air caught my eye, and another glance showed me that it was carried on a stick by a man who was moving among the broken ground. It was Stapleton with his butterfly-net. He was very much closer to the pair than I was, and he appeared to be moving in their direction. At this instant Sir Henry suddenly drew Miss Stapleton to his side. His arm was round her, but it seemed to me that she was straining away from him with her face averted. He stooped his head to hers, and she raised one hand as if in protest. Next moment I saw them spring apart and turn hurriedly round. Stapleton was the cause of the interruption. He was running wildly towards them, his absurd net dangling behind him. He gesticulated and almost danced with excitement in front of the lovers. What the scene meant I could not imagine, but it seemed to me that Stapleton was abusing Sir Henry, who offered explanations, which became more angry as the other refused to accept them.
The lady stood by in haughty silence. Finally Stapleton turned upon his heel and beckoned in a peremptory way to his sister, who, after an irresolute glance at Sir Henry, walked off by the side of her brother. The naturalist's angry gestures showed that the lady was included in his displeasure. The baronet stood for a minute looking after them, and then he walked slowly back the way that he had come, his head hanging, the very picture of dejection.

What all this meant I could not imagine, but I was deeply ashamed to have witnessed so intimate a scene without my friend's knowledge. I ran down the hill therefore and met the baronet at the bottom. His face was flushed with anger and his brows were wrinkled, like one who is at his wit's ends what to do.

Où j'en suis dans mon devoir

J'ai besoin de trouver une problématique et un plan détaillé mais je suis nulle pour ça :( 

Merci d'avance <3