If you want to land this big client you have to take a risk. You can't get the cub without going into the den.
Tips
history
The full proverb is 不入虎穴，焉得虎子, 'if you don't go into the tiger's den, how will you get its cub?' The 后汉书 gives it to the general 班超, rallying his 36 men for a night attack on a far larger Xiongnu embassy. 焉 is classical 'how'.
