When Kevin and Vanessa try to land a security gig at a toy store, they get sidetracked practicing their new business pitch and wind up locked in the store after hours. Also, Chale is having success working at Enzo's.

When Lucifer discovers his ex-fake-wife, Candy, has gone missing, he hightails it to Las Vegas with Ella in tow. Together, the two of them work to find her, but interesting secrets are revealed along the way that could compromise the investigation. Meanwhile, Chloe is upset that Lucifer left on her birthday, so Linda tries to lift her spirits.

While tracking a device that can prevent a nuclear meltdown through the Los Angeles sewers, Walter learns the nuances of listening and not offering advice to Paige. Also, Team Scorpion meets Florence, their new neighbor at the garage, after she sends a mix of smelly chemicals through their shared ventilation as a warning to keep the noise down.

When multiple children get sick from lead poisoning, Morgan Edge points the finger at Lena and blames her creation of the lead bomb she made to save National City from the Daxamites. While Lena knows she never intended any harm, she fears there may have been a flaw in her design, leaving her responsible. Kara teams up with Samantha to clear Lena's name, but it turns out to be harder than they thought. Meanwhile, Alex and Maggie make a crucial decision about the future of their relationship.

Kelly Clarkson helps coaches Miley, Jennifer, Adam and Blake get their artists ready to select their songs and compete head-to-head while their competitors watch.