When Zordon had told Alpha to scan for any place matching the description of the room that Jason had apparently given him while Tommy had been checking on the rest of his friends and fellow Animorphs, Tommy found himself nearly as unsettled as he'd been when he and the rest of the Animorphs had gone down into the Yeerk Pool themselves. Once Alpha had managed to find a way around the interference, which was probably the reason that no one else had managed to find the cavern despite the sheer size of it, Tommy found that he wasn't the only one unsettled by the sight of the cages, the eating area, and the main Pool itself.
"Wha… How did we miss this?" Jason demanded, as the Viewing Globe swept slowly over the interior of the Yeerk Pool.
"Ai yi yi, it looks like the Yeerks have some kind of dimensional interference in place," Alpha fretted, hurrying between the monitoring consoles that stood nearest the Viewing Globe. "It's layered enough that no one who didn't know what they were looking for would know there was anything at all under Century City!"