Mary Morstan has received a pearl in the post every year since her father's disappearance. This leads Holmes and Watson to the truth about a secret pact between four convicts during the Indian Rebellion of 1857.
1965
1987
1971
1931
1974
2015
2000
2009
2004
1972
1905
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2018
2017
2019
1963
1978
1959
2020
