You're a London tube driver and you've had two 'one-unders' in as many weeks. You're traumatized but completely blameless. Then you're told about the 'Three and Out' rule; three fatal accidents within a month and you're out of a job... but with a huge pay off! What do you do? Take trauma counselling and drive very, very carefully? Or do you seek out a third 'one-under', take the cash, pay off your debts and retire to a Scottish idyll to write your novel?