Moments ago…
When Atlas saw Hugo and Zoren running out of the gymnasium, he immediately knew something was wrong. After all, when he saw how Penny smirked right after drinking, he stayed as far away from her as he could.
She could do something terrible to him, and he wanted to avoid that at all costs.
However, when he saw his brother and brother-in-law leave, he followed, just to make sure. At the end of the day, he was still Penny's brother and family. Despite his fear of what could happen if she got her hands on him, he was concerned. Thus began the search.
As Atlas checked every location where Penny could've hidden, he found himself in the men's locker room. He wouldn't have stayed and continued searching if not for the fact that he noticed his locker wasn't locked properly. When he checked, he was able to open it without much effort.
There, he saw his phone turned off.