 During his time as a landscaper he was discovered by actress Gloria Henry, who played the mother on the "Dennis the Menace" television series.Henry learned of her gardener's acting aspirations and was impressed enough by Armstrong’s good looks to arrange for him to get a screen test at Columbia Pictures, where she was under contract.He landed a supporting role in the third season of the television show "Manhunt", playing Detective Carl Spencer in 13 episodes in the 1961 season.