Hayate the Combat Butler Vol. 20 (manga)

Wataru and Saki have flown to Vegas on a Golden Week vacation that they can't afford, with the deeply questionable plan of winning the money for a ticket back home. Instead, Saki finds herself playing the Strip's most ruthless card shark - Wataru's reprobate mother - with Wataru as collateral.

There's plenty of fear and loathing in Las Vegas tonight, but at least things are going better for Hayate and Nagi, sunning with their friends on the Greek isles. That is, until they stumble into an honest-to-goodness labyrinth...