A two-over-one response is game forcing except in competition where it shows ten points and promises a rebid. This is the same as for Standard American. As a result, one needs to know Standard American well before learning any new system.
The bidding: South, with 17 HCP’s, opens his five-card major with a One Heart bid. West has 12 HCP’s and a good six-card Spade suit and overcalls One Spade. His hand is too strong for a Two Spade bid. Furthermore, one does not pre-empt the auction with a four-card major or an opening hand unless partner is a passed hand.
North has nine HCP’s and a very good five-card suit so he bids Two Clubs. This is not game forcing, as it only shows ten points. The Queen Jack doubleton is not wasted as this is partner’s bid suit.
South has a big hand and jumps in clubs. He could splinter by making a Three Spade bid, showing four-card support, Spade shortness and extra values, but one does not splinter with a singleton honour.
North chooses a Four Heart contract instead of Five Clubs. The two heart honours should prove useful. Four Hearts scores better and is one level lower.
The Play: West leads the Queen of Spades asking partner to drop the Jack or give count. East obliges and drops the Jack. West knows he can safely play Spades without losing a trick.
Declarer draws trump and then plays clubs. West wins the ace and returns a Spade. Declarer ruffs with his last trump, and to play it smart, he cashes the Diamond Ace. West likely has the King, and declarer makes sure he does not lose the diamond finesse to a singleton King. West is marked with this King because East could not muster a simple Spade raise. Declarer makes +680.
If declarer takes the diamond finesse without paying attention to the bidding, he will be down. To play it safe and make 11 tricks, he takes five Hearts, four Clubs, one Spade and one Diamond. When he takes the Diamond Ace, he gets a 12th trick.