what episode does benedict find out who sop...

Benedict does not find out who Sophie is in any episode of Bridgerton season 4, part 1.

Quick answer

• In episodes 1–4 of Bridgerton season 4 (Part 1), Benedict is still in the dark about Sophie being the mysterious “Lady in Silver.”

• The part 1 finale (episode 4) ends with their stairwell kiss and Benedict asking Sophie to be his mistress, which proves he still hasn’t connected that she’s the masked woman from the ball.

• Articles and recaps explicitly state that he “never really finds out who Sophie is” and “fails to discover” her identity in Part 1, implying that his realization will only come in Part 2 (later episodes not yet released).

So, if your question is “What episode does Benedict find out who Sophie is (Lady in Silver)?” the current situation is:

As of season 4, Part 1 (episodes 1–4), there is no episode yet where Benedict actually learns the truth about Sophie’s identity.

Fans on forums are speculating it might happen around episode 6 or 7 in Part 2, but that’s just prediction, not confirmed plot.

Information gathered from public forums or data available on the internet and portrayed here.