The Weinstein Company has just sent out a press release informing us that Jeremy Piven has joined the cast of Robert Rodriguez' Spy Kids 4: All the Time in the World.  Piven is set to play the villainous "Timekeeper" who threatens to take over the world.  In addition, Antonio Banderas, Danny Trejo, Alexa Vega, and Daryl Sabara are all set to reprise their roles from the previous films.  They'll join the previously-announced Jessica Alba and Joel McHale.

The Weinstein Company has also revealed the film's official plot synopsis, which you can check out after the jump.  Spy Kids 4: All the Time in the World is due out in 3D on August 19, 2011.

Here's the official plot synopsis for Spy Kids 4: All the Time in the World:

On the surface, Marissa Cortez Wilson (Jessica Alba) has it all...married to a famous spy hunting television reporter, a new baby and intelligent twin step kids.  But in reality, trying to mother Rebecca (Rowan Blanchard) and Cecil (Mason Cook), who clearly don’t want her around, is her toughest challenge yet.  Also, her husband, Wilbur (Joel McHale), wouldn’t know a spy if he lived with one which is exactly the case - Marissa’s a retired secret agent.

Marissa’s world is turned upside down when the maniacal Timekeeper (Jeremy Piven) threatens to take over the planet and she’s called back into action by the head of OSS, home of the greatest spies and where the now-defunct Spy Kids division was created.  With Armageddon quickly approaching, Rebecca and Cecil are thrust into action when they learn their boring stepmom was once a top agent and now the world’s most competitive ten year olds are forced to put their bickering aside and rely on their wits.  With a little help from a couple of very familiar Spy Kids, Carmen (Alexa Vega) and Juni Cortez (Daryl Sabara), and some mind-blowing gadgets, they just may be able to save the world and possibly bring their family together while they’re at it.

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