story: At first the Wilcos thought getting a puppy was a good idea. It was cute and playful and small. Then it started growing and playing harder. Now they're too afraid of it to let it out of the basement. It won't let them call animal control and they don't know what to do.
 selected sentence: Then it started growing and playing harder.
The puppy starts playing harder >Causes> The Wilcos feel(s) concerned