Jeremy Smyth, of Smyth Industry, lies dead in his bed. The bedroom door locked from the inside, his right hand rests beside his head, still holding the revolver. Everything points to suicide. But Holmes harbours his doubts. Questioning the relatives reveals that Mr Smyth was fond of horse racing and had wagered considerable sums. But do his gambling debts have anything to do with his death? Meanwhile, Holmes and Watson pursue their own personal wager, which brings an unexpected conclusion.