Tony and his brother Joey played with the compaction frame (a cosmic object that actually contains and entire universe within a small frame) that his father brought home one day after discovering it in the Puppet Master's cell, and The Puppet Master missing, from Ryker's, where he was employed as prison guard.
The two boys loved it at first as the compaction frame allowed the puppetverse contained within to slowly expand onto Earth, at first just forming a small island in their backyard where they could play with the puppets that came through. When the evil puppets broke through however and set their neighbor's house on fire, their father was arrested for the crime.
This is where She-Hulk (in her duties as a lawyer) came into play. Along with her allies Weezi Mason and Phantom Blonde, and a little help from the cosmic being known as The Critic, they were able to find and recapture The Puppet Master and put the puppetverse back into it's compaction frame where it belonged.