12/06/2013 01:51 pm ET Updated Feb 05, 2014

'Big Bang Theory' Recap: Sheldon's Big Problem Returns

It's not often that "The Big Bang Theory" recaps what's happened in previous episodes at the top of the show. This show doesn't typically do long arcs or deep callbacks, but instead it engages fans with familiar character traits, established relationships and quippy punchlines. It's one of the most retro comedies on TV right now and yet, perhaps because of this, the most popular. "The Discovery Dissipation" tries to have it both ways. We get a surprising continuation of a previous storyline, but also a retread of some of the more troubling parts of the show.

It helped that tonight's episode continued a story from one of its best episodes of the season. It was four episodes and over a month ago that we saw Sheldon discover a new element only to realize he did it completely by mistake. Building up Dr. Cooper and then taking him down will always be a good combination for "Big Bang" and it gave Jim Parsons a lot of room to really play around. Picking up where that superb episode left off was a smart move and brings a level of depth that this show doesn't typically do. Sheldon's "discovery" would, in the real world, have many repercussions, so it was great to see some of those play out.

The episode mostly focuses on Sheldon's lingering internal conflict and his friends trying to help him. Starting with a disastrous radio interview and leading up to a very sad toy train session, these exploits allow for the return of some welcome familiar faces. Wil Wheaton is back with a performance that feels like an after-school special, and isn't helped by Parsons' infantile performance in the scene. (Though the meta joke about Wheaton's career was funny on an insider level.) John Ross Bowie also returns briefly as Kripke (one of my favorite "Big Bang" fringe characters) with enough screen time for the show to finally acknowledge his speech impediment.

Leonard eventually disproves Sheldon's discovery (that was convenient), and Sheldon goes on a humorous rant about his 10, no 9, no 8 friends -- science, naturally, being his best friend. Booking ending the episode with a second radio interview was also a nice touch. In the end, this episode didn't shine as much as "The Romance Resonance," but Parsons got to play a range of emotions that largely made his element problem worth revisiting.

Where Sheldon's story was a continuation from previous weeks, the Howard-Raj-Bernadette situation was essentially a repeat. We're told Raj is going to stay for a week with Howard and Bernadette, so naturally, hijinks are going to ensue. Let's see ... Howard is rude. Bernadette is angry. And Raj is irritatingly thoughtful. Again. We've been seeing these dynamics in some form all season long and if it wasn't so frustrating for all involved it may have been permissible. Unfortunately, it only makes me despise the characters, especially Howard and Bernadette. The married couple get mad at each other because they realize Raj is a better spouse than either of them, and at one point Raj jokingly questions why they're married. Funny, I was thinking the same thing, but it wasn't a joke.

In its Thanksgiving episode "Big Bang" took a big swing with a high concept that didn't entirely work, and here they try to pull double duty with a serial story and an episodic one. The show typically is very successful relying on an episodic structure, but tonight the serial outweighed the standalone. Now, I'm going to go watch a video of a koala and an otter being friends.