Telly and Elmo are building an "I" with their new "Letter of the Day" kit, and Elmo imagines things that begin with the letter "I": igloo, insect, and iguana. Suddenly, Iggy the dog takes the letter "I"! Telly and Elmo chase Iggy, but can't catch him. How will they get him to drop their letter "I?"

They think hard and decide to go incognito, or in disguise, as leafy bushes. The bushes make Elmo's nose itch. When he sneezes, he blows their cover and scares Iggy. They think again and come up with another idea: they will tickle Iggy's nose. This works, but the letter "I" goes flying, bounces off of Telly's head, and lands back in Iggy's mouth. They think yet again and decide to give Iggy doggy ice cream. Just when Iggy goes to eat it, Telly tries to grab the letter, but Iggy snatches the letter and runs off and returns the letter to Rosita, since he thought they were playing fetch the whole time! Telly and Elmo realize Iggy inspired them to think of lots of "I" words and they sing all about the incredible Iggy!