What were they thinking?

Unfortunately, that's the first question that pops into one's mind after having to sit through The Big Wedding – the latest ensemble comedy to hit the big screen. Directed by Justin Zackham, best known for his penning efforts in 2007's  Bucket List, the film boasts an impressive cast, but even the who's-who of Hollywood struggle to save the story's ridiculous plot.

The Big Wedding focuses on the wedding day of young couple, Alejandro (Barnes) and Missy (Seyfried). Alejandro's adoptive parents, Don (De Niro) and Ellie (Keaton), have been divorced for almost ten years and Don has been playing house with Ellie's now ex-best friend, Bebe (Sarandon), ever since. Now, the whole family – Missy's parents, Muffin (Ebersole) and Barry (Rasche), as well as Alejandro's siblings, Layla (Heigl) and Jared (Grace) – are bought together to celebrate the happy day.

Things soon get complicated when Alejandro's biological mother, Madonna (Rae), and sister, Nuria (Ayora), also decide to fly in for the wedding. While Alejandro can work his sister's liberal mind around the fact that Don and Ellie are now divorced, the idea wouldn't sit too well with Madonna's conservative mind-set; so, in order to keep things smooth, everyone involved decides that its best to pretend that two are still married.

The plan, of course, seems far easier in theory than in practice, and as the couple starts preparations, the tension and unresolved family drama begin to boil over.

Adopted from the supposedly better 2006 French film, Mon Frere se Marie, Justin Zackham attempts to blend the elements of a screwball comedy and a wacky family drama – one that highlights uncomfortable sexual escapades among sixty-year-olds.

To his credit, the mix is occasionally charming, but sadly, it doesn't have enough wit or drive to sustain credibility. The storyline stands on the verge of complete embarrassment throughout, sinking deeper and deeper into nonsensical subplots, which include thirty-year old virgins, projectile vomiting and sexual innuendos.

For Oscar-winning foursome, De Niro, Keaton, Sarandon and Williams, this isn't exactly a career highlight, but thanks to their god-given talents, they all do just enough to get by. 

De Niro's raunchy one-liners are tolerable, Keaton's restrained character is charming and Sarandon's over-the-top performance is watchable, while as the racist priest, Williams is, well, typical Williams. Surprisingly, Heigl – after a series of disappointing roles – shines.

The Big Wedding is a tragedy of a film that, on paper at least, looked like a hoot. But a directionless script ultimately serves in making this a bit of a stinker.