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An elusive VHS tape will bring Sheldons both big and small together for the first time next month. CBS has revealed the first details of December’s unlikely crossover between The Big Bang Theory and Young Sheldon, and it appears a piece of ’80s TV technology will play a pivotal role in the mashup.

Earlier this month, it was announced that Young Sheldon‘s titular star, Iain Armitage, would make a guest appearance on Big Bang opposite his older alter ego (Jim Parsons). At the time, the network declined to say how it would pull off the crossover, which also features Armitage’s Young Sheldon co-stars Lance Barber (Sheldon’s pa, George) and Montana Jordan (Sheldon’s older bro, Georgie).

Well, in a programming update issued Monday, CBS shed new light on the Dec. 6 episode, titled “The VCR Illumination.” Per the installment’s logline, “Sheldon and Amy are still down about their theory being disproven, but a VHS tape from Sheldon’s past inspires him not to give up.”

The release also dropped a fresh piece of final-season casting news: The Good Fight‘s Christine Baranski will reprise her role as Leonard’s mother Beverly in the episode. And in another interesting footnote, the outing’s story was conceived by all three of Big Bang‘s current (Steve Holland) and former showrunners (Steven Molaro and Bill Prady).