Newly released photos from this week’s episode of The Big Bang Theory preview nosey friends and a guest star whose return may cause a disturbance in the (romantic) force.

It certainly seems like CBS is setting up Sheldon’s mysterious weekly appointment as the main focus of “The 43 Peculiarity,” but a close look at new stills from the episode also yields evidence for Leonard and Penny’s contentious storyline. Check out the photos below!

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The (or rather, this week’s) curious case of Sheldon Cooper looks certain to deliver the laughs as Raj and Howard pursue the truth of Sheldon’s undisclosed 2:45 location. (And if this promo clip is any indication, the answer may also prove somewhat terrifying!) We think – or hope – that Sheldon is just taking a short siesta, perhaps while a recording of his mother croons “Soft Kitty”… but knowing Sheldon, the possibilities are both limitless and exhilaratingly scary!

The photos also confirm that Margo Harshman will return to her role as Sheldon’s cute assistant Alex, and may play a part in stymying Howard and Raj’s attempts to suss out Sheldon’s secret. Alex will also most likely fan the flames of uneasiness which she sparked when Penny observed her flirtatious interactions with Leonard. Between Alex and Penny’s new potential interest Cole, no wonder the on-again-off-again pair look less than thrilled in that last shot.

The official summary from CBS for “The 43 Peculiarity” says:

Howard and Raj try to get to the bottom of why Sheldon disappears every afternoon at 2:45. Meanwhile, Leonard and Penny deal with jealousy in their relationship.

The Big Bang Theory will take a brief hiatus next week, but the show will return on Nov. 29 with “The Parking Spot Escalatio”“:

When the University reassigns Sheldon’s parking spot to Wolowitz, their fight affects the whole gang.

The Big Bang Theory airs Thursdays at 8 p.m. on CBS.