Ace does the usual thing when casing a place out - he parks about a block away, arms the (admittedly excessive) security on his bike and walks the rest of the way over. Real casual like, he leans against the building, adopting a 'far away' look, as if he's deep in a mesh search, same way's you'd see any 'ol guy doin' it.
If this was a cheesy action movie, he'd put a hand to his finger to talk on the secure channel, but it isn't, so it's a silent, less interesting to look at kind of affair. "I tossed some questions the way of a few of my contacts, they should get back to me shortly. For now though, no need to do anything fancy. I'll play the part of a concerned friend. See if I can't find anything interesting out. Maybe ask if I can get a look at his work space. Might be something useful there, never know. . . and hey, if it works, "
That said, into the lobby proper he goes, looking around like. . .a tourist, really. Not apparently paying enough attention catch any really fine detail - he'll trust his eidetic memory to provide a mental 'picture' as it were to go over later - which would seem suspicious, more looking to see what's around.
Finally, he settles on the secretary, his face lighting up in a genuinely friendly smile. "Smile when greeting someone you don't know. First impressions matter the most. " or so his father always told him.
"S'cuse me, (sir or ma'am, whichever is applicable here, if no sex is obvious, if there's a name-tag, he'll just go with what's on the tag) I'm a friend of Rebby -er, Riviera's. He said he worked here. I don't really want to take up too much of your time, but. . . well," he pauses, sighing a bit, shoulders drooping.
"I haven't been able to get in touch with him lately, so I thought maybe the people he works with would know where he is, or if something had happened to him. So, uh. . .do you?"