#5: The Santa Rosa Ladies

Midway through the session, sitting west, you arrive at a table of two charming and seemingly capable young women, who promptly bid to the slam.

You lead the 8.  Dummy plays low, and declarer takes partner's nine with the ace.  The three of spades lead fetches the six, ten, and five.  Declarer now cashes dummy's club king and tries a club to the ten, which you win.

What is your next play, and why?