South takes a wild stab at six hearts and cannot be entirely surprised to see he is missing two aces when dummy comes down. However, he must not give up. He can employ the old trick of covering with dummy’s spade queen at trick one. When this is covered by the king and ace, declarer leads a trump to West, who must decide whether to try to cash a spade or a club trick. (The diamond ace can wait if East has it.) West might easily go wrong, but if declarer had played small from dummy at trick one, West would know declarer had the bare ace — otherwise, why not try the queen in case the king was onside?
This is all well and good, but East can have the final word. West would scarcely underlead the spade ace (and if he did — perhaps with a void in diamonds — he would have selected a smaller card, not the sadistic jack). Moreover, West’s vulnerable weak two marks him with a six-card suit. East can see no future in the spade suit and should therefore play small at trick one. When declarer wins with the ace, West knows to change tack upon scoring his trump ace, and only a club shift can be necessary.
If East does cover the spade queen at trick one, declarer can pile on more pressure by leading a high heart spot (ideally the seven) from hand at trick two. Advancing the two might convince West that East’s heart four is a low card, suit preference, asking for a club shift. That would allow the defenders to recover from their misstep.