Synopsis by Hal Erickson
Filmed between December 12 and 14, 1909, the Biograph "triangle drama" On the Reef was ready for theatrical display within four weeks. Henry B. Walthall plays a grey-haired gentleman, the father of a twenty-year-old girl, who marries Marion Leonard, several years his junior. She in turn falls in love with a man closer to her own age. The fact that her lover is also her husband's best friend rather complicates matters. Not wishing to break his friend's heart, the lover walks out of the woman's life, but not before sending her a letter expressing his undying affection. Alas, the letter is misdirected to the husband, who is so shocked by his wife's infidelity that he suffers a fatal heart attack. With both of the men in her life gone forever, the wife resigns herself to a lonely life, but is "saved" by the friendship of her grown stepdaughter, who has forgiven all.