Temperatures were sent racing on Thursday's new episode of Grey's Anatomy as Addison Montgomery made her grand return.

A lot was riding on the episode because it was the first time Addison was back in Grey Sloan Memorial since 2012.

The new episode kicked off with the residents eagerly awaiting the arrival of someone to help Weber with the residency program.

It was so top secret that even Jo was left in the dark ... until Addison popped up with the following witty line:

"You must be the group that’s been screwing up the program," she said in one of the funniest lines of the series.

Eagle-eyed viewers will notice that this line was a direct callback to Addison's first meeting with Meredith back in 2005.

"And you must be the woman who's been screwing my husband," Addison said on the medical drama's first season finale.

We love a good callback!

The residents were scared of Addison from the get-go, but they couldn't resist gossiping behind her back, mainly about threesomes between her, Derek, and Meredith.

Addison brought a case with her for the residents to work. It involved a uterine transplant for a young woman named Tovah.

She wanted to get pregnant with her husband's preserves sperm specimen.

She explained to the residents that she and her husband had been trying for a kid for years, but she couldn't carry the kid to term.

The husband, unfortunately, died of cancer, so this was a deeply personal case.

In true Grey's Anatomy fashion, the surgery was marred by the AC in the hospital dying. The heatwave was messing with the whole hospital.

Addison knew time was of the essence, so she demanded Meredith scrubbed in to assist her.

There was a lot of playful banter between them as they worked on the surgery.

In the aftermath, Addison broke down. She'd been telling herself that Derek was still alive in Seattle, and his death only felt real when she returned to the hospital.

“Addison, he is here,” Mer told her, citing his children, who would love to meet her.

In turn, Addison told Mer to move on to her next big thing, which would take her away from helping the residents.

This gave Meredith the courage to tell Richard she wouldn't be able to help with the residents for the foreseeable future.

Addison also had a reunion with Amelia, before arriving at Mer's home to meet Derek's kids. Addison's back, and we hope she sticks around.

Elsewhere on this great installment:

- Teddy and Link worked together to restore the AC, but they settled for a cool room in the morgue, handing out snow cones and such. Fun, right?

- Winston asked Owen to help transplant the kidney for the patient, but they couldn't do it in the hospital without Bailey knowing. The solution, Ben's Station 19 aid car.

- Meredith confirmed her intention to work in both Seattle and Minnesota

Catch new episodes of Grey's Anatomy Thursdays at 9 p.m. on ABC.