We flash to Marissa's end of her volatile, final conversation with Sean, and throwing the phone across the room afterward while Walter pounds irritably on the wall on the opposite side. Marissa then moves to ripping up pictures in her fury, and telling what she believes to be her hotel neighbor -- and not, say, a sociopath always on the lookout for any excuse to kill -- to "Shut up, damn it!" And that's all the excuse Walter needs to come in, pound on Marissa, and decide that she's due to deliver right then. Thank you, CSI, for making me feel old and prudish the moment I ask, "Did we really need to see that again?"
So Beth, eyes darting all over the place, says calmly, "He'd always find an excuse for anything that he did." She then checks the time. Catherine asks, "Are we keeping you from something?" Beth lies that they're not, adds that she's really uncomfortable talking about Walter, then whips off her jacket so we can all see the burn marks down one side of her arm. Catherine asks if Walter gave her those burns, and Beth says that was an accident on the job many years ago.
"When you used to be a waitress...Libby?" Gil asks. Why, yes. He explains that he found her old waitress uniform in Walter's car. Well, that's one mystery down. We still don't have an answer for Walter's fever, or what he did for 38 years (besides kill two people that they know of, and spirit a baby off somewhere), but thank the sweet baby Jeebus that we have cleared up the mystery of the missing waitress. Libby asks Gil, "Why would he keep that?" Good question. Just don't expect any answers any time soon, okay? Catherine watches a school bus pull up and thinks, "That long, yellow vehicle...someone I'm familiar with rides something like that...why am I thinking of this? Where is this idea coming from?" Actually, Gil hears the bus too -- because he now has super-hearing, I suppose -- and Beth gets an Oh, crap... look as she realizes the two of them are studying the school bus and watching a towheaded boy come barreling up the front walk.
He comes in and tells Beth, "Hi, Mom." She kisses him hello and gets him out of living room. The boy stares at Gil; Gil stares back, curious. When the boy leaves, Gil asks, "How old is that little guy?" Yes, Gil asks that, and not, say, Nicky. I can't explain it either. We're about two episodes from Gil tousling someone's hair and calling him "Champ." Beth says her boy is going to be nine next month, and Gil and Catherine exchange triumphant looks. I hope their expressions can be pinned to relief that Walter didn't kill Marissa's baby, and not to the joy of smoking Beth out of her den of lies.
Now, a brief scene in which we see Catherine taking DNA samples from the boy (so Beth presumably gave consent, or else it is indeed possible to put together a warrant based largely on supposition -- and it may be) while Gil takes one from Sean. Catherine slaps the results on the table in front of Beth and says, "You're not his mother." "I'm the only mother he's ever known," Beth shoots back.