North’s four-club bid was a cue bid inferentially agreeing on hearts as trumps. North would not have jump shifted to two spades with a two-suited hand unless the second suit was a fit for partner – hearts in this case. South showed a diamond control and North used the Grand Slam Force, asking South to bid a grand slam with two of the top three hearts. You might quibble with the auction, but the final contract was sound.
South saw that he could probably ruff all three of his clubs in dummy. He could discard two of his diamonds on the top spades, but what could he do about his third low diamond? A different plan was needed. He would have to develop dummy’s spade suit. That would be easy if the spades split 3-3 or 4-2, but South took extra care so that he could also handle a 5-1 spade split.
He played the ace from dummy on the opening trump lead and ruffed a spade high. A heart to dummy’s jack drew the last trump and he ruffed another spade, noting West’s discard. A club ruff was followed with another spade ruff, establishing the rest of the suit despite the 5-1 split. Another club ruff got him to dummy and he discarded all three of his low diamonds and his last club on the spades. Note that the contract would have failed had South played low from dummy on the opening trump lead. Well done!