I don't have a direct link to one offhand. I went to business school and worked in business consulting for many years, so writing a plan was sort of second nature to me. I'd offer a copy of mine from my cake business, but I have no idea where it is some 8 years later.
Your local small business association or commercial lender could certainly give you a good guide as to what it should contain, particularly if you're seeking financing. I'd start there - but basics should include concept/mission statement; target customers; profile of competition and how you're distinguished from them; market overview (to gauge your potential market share and revenue); financial projections; etc.