Young Ned has finally saved enough money to be able to buy a pet that he has been wanting. When he gets to the pet store, the only animal he can afford is a newt, which he quickly tires of because the newt, who Ned has unimaginatively named Newton, doesn't do much. When Ned goes back to the store to voice his displeasure, the proprietor gives him a can of special pet food but warns him not to feed the creature too much of it. Ignoring the warning, Ned overfeeds Newton, who subsequently turns into a 500-pound monster. The now-giant newt becomes a mischievous and empathetic playmate for Ned, always there to lend an ear when Ned needs some encouragement.