Extreme climber Andreas Marthaler has returned to his home in Styria, the rugged mountainous region of Austria, for the first time in three years. He has come to be the best man at a wedding: his closest friend Stefan Hofer, head of the mountain rescue service here, is getting married to Emilie. In fact they have been together for many years and have two children already.
This is to be Andreas’ last day in the area where he was born. He has great plans for the future: together with his girlfriend Sarah, he intends to open a mountaineering school in Grand Canyon.
The morning after the wedding the two friends take a last opportunity to have a look at the mountain world they have known since childhood before their lives change forever. They get up early and go for a peaceful climb together. But suddenly they notice a climber on a rocky outcrop below them: apparently he has fallen and is hurt.
Andreas and Stefan immediately start to make their way down to the injured man. But although they are experts and take every possible precaution, they can't prevent the avalanche which now begins. Stefan suffers a severe blow to the head and falls. He only just has time before he dies to beg his friend to look after his wife and the children.
Devastated, Andreas now faces the terrible task of breaking the tragic news to Emilie. It is hardly surprising that she blames him: after all, he was the one who persuaded Stefan to go on that last climb together. She is furious and announces that she hopes she will never see Andreas again. With a heavy heart Andreas prepares to leave, determined not to stay in Styria a second longer than absolutely necessary.
But Stefan’s son, eight-year-old Lukas, simply refuses to believe that his father is dead. He slips away and sets off up the mountain to find him. When Andreas hears what has happened he doesn't hesitate for a second: he immediately heads off to look for the boy.
The waiting is unbearable for Emilie. She has just lost her husband – is she now to lose her son as well? And will Andreas keep the promise he made his best friend just before his death?