Monk (2002)

S1E8 Mr. Monk and the Marathon Man

Monk, a one-time marathon runner, uncovers a devious plot orchestrated by a wealthy furniture tycoon to eliminate his mistress amidst the chaos of a city marathon. As the race unfolds, Monk's keen observational skills lead him to piece together the clues, revealing the sinister intentions behind the seemingly innocent event. With time running out, he must race against the clock to expose the truth and prevent a crime from occurring in plain sight.