The Devil's Foot (S04E02)

After a bout of illness, Holmes begrudgingly retreats to Cornwall for a vacation, accompanied by Watson. However, their peace is shattered when they learn of a bizarre death. Following a tranquil night of playing cards, three residents are discovered the next morning in a shocking state: the two brothers have succumbed to an abrupt madness, rambling nonsensically, while their sister lies lifeless, her expression frozen in horror. Intrigued and eager to escape his holiday tedium, Holmes eagerly embraces the opportunity to unravel this perplexing mystery.