Review: Kaley Cuoco keeps delightfully unhinged 'Flight Attendant' Season 2 in the air

It's nice to see Kaley Cuoco fly the friendly skies again.

HBO Max's comedic thriller, "The Flight Attendant," returns for a zanier and more intense second season Thursday (streaming weekly, ★★★ out of four). It wasn't a show whose murder mystery plot demanded a new chapter, but Cuoco's performance as an alcoholic flight attendant was worth revisiting.

Season 1 earned the actress an Emmy nomination, and her full-throated commitment to the role has not diminished as Cassie Bowden attempts sobriety and tries to get her life together. The comedy is still there, as are some cringe-inducing moments and head-scratching decisions, but there is also a more serious, introspective tone to the new episodes.

Although the plot mechanics that return Cassie to the international crime scene are a bit silly (she's a CIA asset now because why not?), Cuoco and the writers make the show click by mirroring the structure of the first season without directly copying any of it. Once again, Cassie finds herself in over her head and falls into a self-destructive streak trying to fix it all.

Season 1 review: Kaley Cuoco easily departs 'Big Bang' in silly-but-thrilling 'The Flight Attendant'

We meet up with Cassie one year after the events of Season 1. She's relocated to Los Angeles and celebrating a year of sobriety, regularly attending Alcoholics Anonymous meetings, thriving at her job and in a stable relationship with a fellow AA member. She's spending her free time, while flying around the world as a flight attendant, moonlighting for the CIA, grabbing photos and intel in far-flung locations. It's all going swimmingly until Cassie goes beyond the scope of her CIA assignment while in Berlin, where she finds a woman who might be impersonating her and is nearly killed by a car bomb.

As she deals with the fallout, Cassie is also working hard on her sobriety journey, cheered by her brother Davey (T.R. Knight) and her best friend Annie (Zosia Mamet) and Annie's boyfriend Max (Deniz Akdeniz). Her former co-worker Meghan (Rosie Perez) is on the run from the American government and North Korean assassins after unwittingly committing treason. Cassie may think she has her life together, but one crisis shows how precariously she balanced it.

Cuoco is superb, perhaps even better than last year's performance as she's had time to refine her character. One fantastic change is in the scenes that take place inside Cassie's head. This time, Cassie argues with different versions of herself rather than imagining her murdered one-night stand.

It gives Cuoco more to do – she seems to delight in playing angrier, cattier versions of the character – and ensures Cassie remains the emotional center of the series: a damaged, well-intentioned, struggling woman who still doesn't quite know who she is, even after everything she's been through. The mystery, the thrills and the gunfights are still there, and it's all very exciting (and even more ridiculous than Season 1's murder mystery), but "Flight" is at its best in scenes that are about Cassie's internal life, including one in which Cassie confronts her mother (Sharon Stone, an absolute treat).

"Flight Attendant" is the kind of show that brings up a lot of questions: about substance abuse, mental health, relationships, and why the CIA would ever consider this woman reliable enough to work for the agency. It seesaws from wildly comedic in one moment to devastatingly sad in another. It is sometimes a bit nonsensical but it is always gripping, which is what a series like this most needs to be.

Without Cuoco, it would probably be forgettable, but she makes it worthwhile to tune in. Even if Cassie isn't a very good spy.

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This article originally appeared on USA TODAY: 'The Flight Attendant' Season 2 review: Kaley Cuoco makes it work