It should include a market research that identifies your competitors, their share of the market and the range of the products they produce. By learning how they conduct their operations, you may learn tricks of the trade in the business you want to enter and you also get to have a basis on what you can do to excel.
Set out a basic management structure outlining who has responsibility for various aspects of the business. This will be easy in the beginning but eventually you may have marketing staff, administration staff, kitchen staff and servers. Make it clear how you plan on delegating tasks, leadership and responsibility for decision making down to your employees.
A plan may be essential in order to prove that your concept is viable when it comes to talking to investors or seeking funding from other sources. However, even if you are independently funded and have nothing to prove to anyone a plan will still be useful. It will help you to confirm that your plans are indeed possible and it will give you a place to compile all the data that you collect from your research.
If your answer is no, you may have been able to easily accomplish this goal by planning for such expenses in advance through a business plan. Even if having cash at the ready is not a viable alternative for you, you may have planned to have a line of credit available for such opportunities, knowing that in your field these opportunities do arise from time to time.