When Alex agrees to let his ex-fiancé Chloe crash on his couch during her stay in town without notifying Whitney, he finds himself in trouble. Instead of consoling his current significant other, he has to cater to his ex, putting Whitney in an awkward situation. Meanwhile, Roxanne lets Lily use her apartment for some alone time with a date and ends up crashing for the night with Mark.

With the war intensifying overseas, Gladys is inspired to organize a fundraiser for Canadian POWs, which her parents commandeer for their own means.

Chris and Nick argue about who is to blame for Sheila's introduction into their lives. Gary discusses his life before becoming a stay-at-home dad and the origin of his chipped tooth. Meanwhile, Chris and Sheila patiently await the arrival of Ernie's first word.

In April, 2010 the eruption of Iceland's Eyjafjallajökull volcano turned much of Europe into an ash-strewn no-fly zone, stranding millions of travelers. But was Eyjafjallajökull just the start? Now, an even more threatening Icelandic volcano, Katla, has begun to swell and grumble. Two more giants, Hekla and Laki, could erupt without warning. Iceland is a ticking time bomb: When it blows, the consequences could be global. As CGI takes us inside these geological monsters, we meet atmospheric scientists who are working to understand just how devastating an eruption could be-not just for air travel but for the global food supply and for Earth's climate. Could we be plunged into years of cold and famine? What can we do to prepare for the disaster to come?

Enrique Rodriquez, a working-class Catholic man is determined to seek justice for his sister when he finds out that she's part of a church cover-up. The scandal is made public when Father Shea, a priest, is pulled from his car and brutally beaten. When the police arrive, they arrest Fin's ex-wife's brother, Sam Randall. Despite Sam's former criminal record and various stints behind bars, Fin doesn't think Sam is their man and asks his SVU partners for help getting to the bottom of the case.

John sets up an illegal buggy race in a desperate attempt to repay his debts; Esther reveals something that could shift the balance of power.

Blades are drawn in this week's Quickfire Challenge, and we'll find out which cheftestants' knife skills are truly on the cutting edge. In the Elimination Challenge, tribute is paid to the most memorable moments in Top Chef history, and sabotage is afoot when two chefs cook to save their lives. Judge Wolfgang Puck returns and is joined by culinary super stars Wylie Dufresne, Jonathan Waxman, and Chris Cosentino, as well as head judge Tom Colicchio and host Padma Lakshmi.

Melanie finds herself tangled up in a love triangle at the office; Joy's firefighter fantasy may be ruined by something she learns about Sean; Victoria's relationship with a movie star makes her feel insecure; Elka and Mamie have a brush with the law.

Monsignor Howard turns to Jude for advice, while the ex-nun recovers from electroshock therapy. Meanwhile, Thredson returns to Briarcliff in a new position and plots to get ahold of his forced confession tape, and Kit is reunited with Grace.

Eaten up by his guilt over Flaco's death in the fire, Cruz goes to Casey to confess. While Shay recovers from a head injury sustained in the ambulance crash, Severide asks Dawson for her help in dealing with his own injury. Casey is caught in the middle of a family conflict between his mother and sister. Elsewhere, Herrmann finds a business deal hard to stomach.

Clipdown '12 Part 2.

Tickle gets busted by an angry landowner, while Tim devises an ingenious new hiding spot for his back-up stash of shine. Then, Josh & Bill get into a bone-breaking fight at their new still site. Also, Mark bootlegs moonshine by canoe in the dead of night.

Brandon gives Cheston a lesson in drilling; Cheston risks his friendship with Brandon; the landowner reiterates a deadline to Oscar; Brandon has legal troubles.

With Elliot away and a rowdy new neighbor partying next door, Fran thinks life can't get any more frustrating. But when the neighbor shows up with some surprising news about her flower shop, Fran realizes it definitely can!

Kathy Griffin, Chris Pratt, Big Boi

Kevin Hart, Betty White, Dwight Yoakam

As Luc discovers a breakthrough in his research, a patient's tattoo becomes the gateway to a darker side of him. Sacha attempts to help his friend before it is too late. Lilah is back at work and is surprised to learn that Ric has not resigned. Ollie is worried that Tara's reveal the previous week has forced her back into her shell.

Sparks end up flying when the notorious Barry family join the school. Barry Barry causes trouble straight away after his affair with another pupil's mother is exposed. Scout manages to begin a feud with returning teacher Nikki Boston. Imogen is worried that Christine is attempting to keep Connor away from her.