“Party Down,” one of best under-the-radar shows on TV, returns tonight at 10 p.m. for its second season on Starz. It didn’t receive a lot of hype when it debuted last year, and Starz is one of those premium channels that not everyone gets (though if you have HBO, you probably have Starz too), but it managed to find a loyal following and drew critical raves. I’d include it right up there with “Modern Family” and “Parks and Recreation” as the best new sitcoms of the past year.

The R-rated workplace comedy revolves around an L.A. catering company filled with showbiz wannabes and couldabeens, and co-creator Rob Thomas (“Veronica Mars”) has put together one of the best ensemble casts anywhere. There’s new team leader Henry (Adam Scott), who had a brush with fame through a national TV commercial but has resigned himself to a life of slackerdom; former team leader Ron (Ken Marino), who has dreams of owning a chain restaurant franchise, the awful-sounding Soup ‘R’ Crackers; Casey (Lizzy Caplan), an aspiring comedian who always seems to be thiiiis close to landing a role on a sitcom; Roman (Martin Starr), a struggling screenwriter who can barely conceal his utter scorn for pretty much everyone else; Kyle (Ryan Hanson), a vapid blonde actor who relies entirely on his good looks; and new addition Lydia (Megan Mullaly), a would-be stage mom who takes over for the departed Constance (Jane Lynch, who left for “Glee”). The cast members play off each other perfectly, and the result is one big ball of sarcasm and snark with free-flowing, rapid-fire dialogue that feels like improv comedy (though the vast majority of it is scripted).

For non-subscribers, Starz has put two full episodes online so you can get a taste. Season 1 is out on DVD now, and well worth checking out. Here’s the trailer for the new season: