Cut to Warrick and Sara in the maze of pipes where Amanda's body was found, because no watery scene is complete unless Warrick's up to his knees in it. They find the shower curtain. Sara does not, however, use this alone time to give Warrick a vindictive dunk in the water for blabbing about her date to Nicky.
On drier ground, Brass and Gil are racing through the Labitrail, with Brass giving Gil the rundown on Amanda's phone records. The same four numbers popped up frequently: her mom, a pizza place, Logan, and the gym, but Amanda's last logged call is to a cell phone traced to Mrs. Logan. Conveniently enough, Catherine comes by with the lab's results for the wine glasses: the saliva samples on both come from women, one from Amanda, the other currently unknown.
Meanwhile, Sara and Warrick are working on the shower curtain together, gleaning all the evidence they can via visual examination and swabbing. Sara finds a small cut in the curtain; Warrick hypothesizes that it happened when Amanda's finger was cut off. We get to see the cutting in slow motion. Warrick then bends to another smudge; he and Sara don't think it looks like blood, and when they test it with luminol, it doesn't glow. Sara notes that it's a greasy stain; upon further analysis, it turns out to be peanut butter. Liam asks, "Did you guys clean the table before putting the curtain on it?" Warrick gives him a girl, please look, and Sara grins indulgently before drawling, "Yeah." Liam continues, "'Cause I think your evidence got contaminated." Warrick's look changes to that of a Jerry Springer guest who's just been informed that the parent/sibling/paramour/all-of-the-above they've been gleefully trashing is, in fact, waiting backstage for a tête-à-tête. Sara looks as though she's in denial. Liam explains that they've got peanut butter in their lab evidence. And going by the look on Sara's face, those aren't two great tastes that go great together. Nicky happens to be wandering by, and Warrick asks if he's been running around eating peanut butter. Nicky disavows any taste for the product, and Warrick's all, "Well, it's on the back of that shower curtain." Instead of replying, "And you're telling me this because it concerns me how...?" Nicky flashes back to Little Logan eating his PB&J in the car.
Cut to the Young Turks tearing the Logan SUV inside out. Warrick comments, "I need to take my car to this detailer. Not bad." Nicky has no time for Warrick's automotive chitchat, and clues us all in to the fact that cleaning a surface with a carpet cleaner only pushes the dirt further in. Keeping this fact in mind, they find a patch of carpet with a dark blotch. Nicky cuts it out, then looks up at Sara and Warrick to reiterate, "Did I mention how much I hate peanut butter?"