Another in the genre of Sequel-to-a-great-love-story-after-the-first-love-is-gone, a la
Oliver's Story and
BBM2.
From IMDb:Where 'WILLARD' ended... Ben begins. And this time, he's not alone!
A lonely boy, played by Lee H. Montgomery, becomes good friends with Ben, a rat. This rat is also the leader of a pack of vicious killer rats, killing lots of people. The authorities succeed in destroying the rats, leaving the boy in desperate tears ... until he discovers his friend Ben to be still alive!