"The Boscombe Valley Mystery", one of the 56 short Sherlock Holmes stories written by the British author Sir Arthur Conan Doyle, is the fourth of the twelve stories in The Adventures of Sherlock Holmes. It was first published in the Strand Magazine in 1891.

Lestrade summons Holmes to a community in Herefordshire, where a local landowner has been murdered outdoors. The deceased's estranged son is strongly implicated. Holmes quickly determines that a mysterious third man may be responsible for the crime, unraveling a thread involving a secret criminal past, thwarted love, and blackmail.