Rumors abounding the halls of the Grey Sloan Memorial Hospital will reach their zenith in the upcoming winter finale of the ABC series "Grey's Anatomy."

In "Things We Lost in the Fire," CarterMatt reports that the doctors' secrets are about to unfold as the hospital becomes inundated with hurt firefighters from a nearby wildfire. First off, Callie (Sara Ramirez) will learn that Jackson (Jesse Williams) and April (Sarah Drew) slept together. Last episode, the estranged couple got together to talk things out. April wanted to take the opportunity to make amends with her husband, while Jackson wanted to discuss divorce. But instead of talking about lawyers and necessary stuff, they ended up in bed together. What will happen next for "Japril"?

Meanwhile, Maggie (Kelly McCrary) will reportedly struggle to treat Andrews (Giacomo Gianniotti) as a colleague at work. After their hot tryst last episode, keeping things professional between them is hard for the head of cardiothoracic surgery. The hot intern may prove to be more of a distraction for her. Will she be able forget her fantasies and focus on the work at hand? Elsewhere, trouble is brewing between Jo (Camilla Luddington) and Alex (Justin Chambers), as the former questions him about his priorities.

Also in episode 8, viewers will get some more inside details on why Owen (Kevin McKidd) hate Nathan Riggs (Martin Henderson). Last episode, the redhead's post-traumatic stress disorder began resurfacing due to the hunky doctor from New Zealand. When Owen learned that Nathan has been hired by Bailey (Chandra Wilson), he told her that she would regret what she did. When Meredith (Ellen Pompeo) asked him what was his problem, however, he refused to tell her. The promo shows Owen finally crack up, as he throws a punch at Nathan's face. What exactly is the surgeon's issue with the new doctor?

"Grey's Anatomy" season 12 airs Thursdays at 8 p.m. EST on ABC.