Okay, I get that Donna's image of herself as supremely competent and all but infallible has been shaken to its bedrock foundations, but even in that state she had to understand that shredding the document would just make the situation worse. Especially with Mike all but blackmailing her, and especially considering her speech to Rachel in last season's finale about how there are some things you can't come back from.
Cut to Hardman's office (I'm glad he insisted on the taupe walls so I can distinguish it from Jessica's), where Harvey has just told Hardman, Jessica, and Alison what's what, and that he still wants to go to trial. Alison strongly advises the partners to cut a deal instead. Harvey reminds them that they're all supposed to be on the same team, and tells Alison that while she wants to lose small, he wants to win big. "She's the one who has to try the case," Hardman reminds them. Harvey insists that he never saw the memo, but Alison doesn't think he'll be able to convince a jury of that. Jessica tells her to set up the meeting to cut a deal. "And whatever you're thinking, I don't want to hear it," Jessica warns Harvey. Luckily for her the ads are on then.
Mike walks significantly into a courtroom. Cut to him trying to lead Marco's father into confessing to a pattern of abuse against Marco -- or at least into getting him to lose his temper on the stand, which he does, calling Mike a "lying little piece of shit." "And there it is," says Mike with satisfaction. After all, most of his formal legal education probably came from watching A Few Good Men.
At the firm, Rachel surprises Louis, who snaps at her. She starts to lecture him about treating people a tenth as nice as he treats his cat, until she notices that he's red-faced, and holding a cat collar in his hand. Catching the snap, she comes over sympathetic as Louis opens up somewhat about his cat's tragic death. He ends up scampering out of there, just as Mike shows up. Mike asks Rachel if everything's okay, and she says it's not, telling his suddenly-guilty puss, "Not everything's about you, you know." "See, now that's where you're wrong," Mike recovers. Rachel asks what's up with Donna. He plays dumb, but when Rachel asks how many secrets he's going to keep from her, he admits that Donna screwed up, "and it's not small." But Harvey's going to fix it. Rachel asks how he knows.