Dr. Catherine Avery (guest star Debbie Allen) is back to take part in a special bladder surgery. She's also there to make Jackson's life miserable. At least, that's what it feels like to her baby boy once he meets Mara. Who is Mara, you ask? Well, she's the pretty young doc Mother Avery brought along on her trip. Jackson initially believes his mom is trying to set him up. That's not the case at all. Mara is more like a spy. She's been tasked with giving Catherine the complete 411 on her son.
Catherine is also in town for a formal benefit. She convinces Richard to be her date for the evening. After all, they've been flirting with each other all day. As for Jackson, he ends up genuinely liking Mara. He even gives her advice about how to handle his mom. The two of them skip the benefit for some passionate alone time in an on-call room. If Mark knew what his protégé was up to, he'd be very proud.
Bailey lets Richard know that he's a good man even though he's been flirting with Catherine. She knows it's harmless. Richard, however, isn't so sure. He's exhausted from taking care of Adele. She rarely knows that's he's anything more than a friend. That's why it feels so good to have Catherine show interest in him. But at the end of the day, he knows he needs to be with his wife. Catherine echoes Bailey's feelings that Richard is a good man.
Derek wants a reluctant Meredith to work with him again, so he puts her on his rotation for the day. Their primary case involves a 27-year-old woman who has a cyst that been causing seizures. The patient also has a benign tumor that Derek wants to leave alone. But when he gets called away, Meredith and Lexie see the tumor is right in front of them. So they remove it. Derek is furious.
Meredith learns that something went wrong during the surgery. The patient has lost the ability to form words. Derek takes the heat when he talks to the parents, as he blames himself for leaving Meredith alone in the OR. Lexie is devastated by the news, but her big sis advises her to suck it up. She needs to let Derek yell at her and know that she's learned from this tragic accident. The incident is also a confirmation that Meredith and Derek can't ever work together.
Alex has been getting pretty flirty with his pretty intern/patient Morgan. Callie warns that this now-available new mom is falling for her resident after lots of late night study sessions. When Morgan's premature baby develops a brain bleed, a panicked Alex begs Derek to help. The infant pulls through, but Alex still has to deal with the fact that Morgan may be falling for him.
Sam is an elderly gentleman who is having a difficult time making the decision to take his beloved husband off life support. Cristina is less than thrilled when pretty nurse Emily offers to help with the situation. That's because she believes this woman is sleeping with her husband. As far as the patient, Cristina's clinical analysis of the situation doesn't carry as much weight with Sam when it goes up against Emily's compassion.
Cristina gives Sam one more honest chat. This one sinks in. He agrees to pull the plug on his husband. Cristina then has another honest chat with Emily. She asks her to stop sleeping with her husband. This direct order was unnecessary, as there was never anything going on between the two of them. Owen confirms that he wasn't cheating on Cristina with Emily. Then he drops the bombshell that he did, indeed, cheat on her. Wow.