The opposition open 1C raised to 1S ending up in 4S - All Pass. You are making the opening lead against a suit contract.
Acol Bidding
The opposition open 1C raised to 1S ending up in 4S - All Pass. You are making the opening lead against a suit contract.
Plan Before You Play
Leads against suit contracts hope to attack the declarer's weakest suit. Avoiding declarers suits which are clubs and spades leaves you with options in the heart and diamond suits so which is the longest and strongest suit in your hand? Lead your 4th highest card from your longest and strongest suit.
The Play
Lead 2H partner plays KH covered by AH instantly promoting your QH to a winning card. Declarer plays their spades eventually losing to partners QS and who leads a diamond, won by declarer, declarer leads out the JH covered by your QH you then run the 10H and 7H. Then switch to your club suit do not underlead the AC you may be giving the opposition an extra trick - lead out the AC and then a low club which partner wins with 10C and then plays the KC. No one cares that the rest of the tricks are declarers - you've punched a HUGE hole in their score
Comment
The correct opening lead and defensive plan results in taking this contract 3 light for 300 points your way. Try leading other suits as opening leads and see how well your side does. Leading a spade a high club or a diamond gives the opposition 10 tricks - leading a low club gives them 9 tricks. The opening lead can be crucial
The above commentary is intended as a guideline only. As with any Bridge hand there are many ways to bid and play any hand.