Final answer:
The 'three broken threads' in 'The Hound of the Baskervilles' are mysterious clues that play a significant role in solving the mystery of the hound's curse.
Step-by-step explanation:
In the book 'The Hound of the Baskervilles,' the 'three broken threads' refer to three incidents that occurred:
- The note found on Sir Henry's boot, which was torn and smeared because the envelope had split.
- The walking stick left behind by Sir Charles Baskerville, which was broken and splintered because it had been used as a weapon to defend himself against the hound.
- The boot found outside the window of Hugo Baskerville's Tower, which was also torn and muddied because it had been used to escape from the tower.
These 'broken threads' are all mysterious clues that play a significant role in solving the mystery of the hound's curse in the novel.