Irv Hartwig was the local blacksmith of the town of Walnut Grove. Irv appeared to be a friendly, kind-hearted man but was actually a stalker and sexual predator who became obsessed with the attractive 15-year-old girl Sylvia Webb. Irv took to secretly observing her from concealed places. Then one day, when Sylvia was picking flowers in a meadow while walking home from school, Irv ambushed and raped her, wearing a clown mask and knit cap to conceal his identity. Sylvia had become pregnant from the assault. (Episode 717: Sylvia (Part 1), (Episode 718: Sylvia (Part 2))