Trick one, H7, king wins, West plays heart Two
Trick two, DQ to DK, DA, D2
There is four lines I want you to consider. The first is the possibility that the Diamond King was played from singleton King, or from K9, K7, or K97.
LINE 1) Lead diamond four, and if WEST plays 2, play D5. This play relies on theory with JT left in dummy, EAST will not cover with king.
LINE 2) Win DJ, if East shows out, duck club and play for a diamond-black suit squeeze on WEST or two black suit squeeze on EAST. This play caters to East having K7 or K9 doubleton and covered out of fear with Ax doubleton or Axx tripleton you might lead low on the second round if he ducks the first round.
LINE 3) Win DJ if WEST has 4D, play for black suit throw in and endplay. Similar idea to line 2.
LINE 4) Cash three hearts to see if you can get distribution clue, saving the potential second round diamond hook until later.

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2N 3C
3N 6N
Pass