Late at night in the office, Donna's phone rings unattended. As you recall, she was fired last week, because she was stupid. Only once, but it was really stupid. Also, it's late at night so she probably wouldn't be here anyway. Harvey lifts and drops the receiver, then dials his cell phone to call his driver Ray with instructions to pick him up in an hour and bring a tux.
Harvey then shows up at Mike's apartment for the first time ever and the tux he's wearing makes him seem even more incongruous in the comparatively squalid space. He makes fun of the place a bit before telling Mike to put on his own tux so they can deal with a "situation" in Atlantic City. Mike has to admit that he doesn't own a tux, which is somehow a surprise to Harvey. "I'm not Bruce Wayne," Mike protests. Harvey is more than aware of that fact.
Elsewhere, another tux-clad partner, :Louis, shows up at the ballet. Which is odd, because Mike's wall clock said it was 9:40 PM. Louis is a little surprised to run into Rachel, who's also dressed pretty schmancy, and they chat about their shared concern over Donna's mysterious disappearance and love for the ballet before the lights flicker. Louis offers her the third-row seat next to him, which he buys as a "precaution." Of course he does.
In the limo, Harvey explains to Mike why he brought an extra tux: "Something told me you'd need it. And by 'something' I mean 'common sense,' and by 'need it,' I mean, 'you're an idiot.'" Mike asks why they're there, but it's a purely Socratic question since he already figures this has something to do with losing Donna. He then asks, "How's that?" while proudly showing off the bow tie he's just knotted at a 45-degree angle. They show up at a casino, which it turns out Mike was banned from for card-counting three years ago. Harvey thinks Mike's tux will serve as camouflage and just when Mike is making fun of the tux thing in the first place, they're met right inside the door by hostesses with free champagne. Hence the tuxes. Harvey asks after a guest named Keith Hoyt, and he's directed to the poker room, despite Harvey's concerns that Hoyt shouldn't be there. As they head in that direction, Harvey exposits that the client has a drinking and gambling problem, but has to be in AC as the keynote speaker at a clean energy conference after being clean for five years. Soon they reach the poker room, where Mike takes a look at one haggard player and Rain Mans that he has over three million in chips in front of him. That would be Keith Hoyt, of course and alas. While they watch, he drunkenly goes all in. Harvey tries to intervene, but the hand plays out and Keith loses. A guy with a red beard tells him a deal's a deal and walks off with a napkin and Keith tells Harvey, "I just lost my company." Well, the good news is that he's probably less drunk now.