Alanna Boatright

Donna and Joe tie the knot, while April attempts to keep the wedding running smoothly. Ron creates an awkward situation between Tom and Lucy. Jen Barkley (Special Guest Kathryn Hahn) arrives at Ben and Leslie’s house with an interesting opportunity.

Arizona's bad day escalates when she advises a patient on a potential double amputation; Derek breaks a promise; Stephanie and Jo find an abandoned baby; the nonfraternization rule leads to a suspension.

When Mona has Spencer pretend to be her boyfriend at her friend's wedding, Spencer realizes that he has had romantic feelings for Mona since college. Meanwhile, Dee Dee decides to break up with her boyfriend when she learns about his matrimonial desires .

Jack and the team search for Tara Patterson (Michelle Horn), a brilliant 16-year-old private-school student who was last seen by her friends at a bus stop. Tara appears to be the perfect daughter, but the honor student was buying drugs, and the agents wonder if her disappearance is related to the pills she uses. Tara was also selling research papers, and the team theorizes that a disgruntled customer could have been involved. One of her friends tells Jack that Tara was dating a married man, but when the team uncovers the truth, the agents discover they may have two lives to save. Series star Anthony LaPaglia's real-life wife, Gia Carides ("My Big Fat Greek Wedding"), guest stars as Stephanie Patterson, the missing teen's widowed mother.