They wanted somebody else for the job, the subject changed the date, the chosen photographer couldn’t do the new date, a better story has fallen through and they need something to fill the gap. It’s the urgent that’s brought about by a series of failures. Your role in it, if not handled carefully, could forever associate you with those failures, despite the fact that you were not even involved at the point that they took place. No matter how good a job you may do you will always be thought of as the person to call when the person they want is not available. Best to try and avoid those if you can.