<human>: Can you give me a shortened version of the text?

So I just got offered a job with a big company for good pay, good benefits, etc. The best gig I've had yet, but here's the problem. My SO bought us tickets to a concert for a band that we will never get the opportunity to see again...ever. While the first week of work is all training(mandatory), the hours have it running until midnight well past the concert (of course which is on the second day of training). The email I was sent by my new job indicated that, while training was mandatory, that if you have any conflicts of schedule to let her know immediately. My question, what excuse do I give them as to why I need to get out early on that day without saying what it really is (I understand it sounds unprofessional of me to be going to this concert, but it really does mean a lot to us)
<bot>: Got offered great new job, second day of work I have a conflict that means I'd have to either call in or give them an excuse, what should I say?