If the franchisee or franchisor are unwilling to provide a copy of the franchise agreement voluntarily, you can obtain it in litigation via the discovery process.
You can also look into obtaining the franchise agreement through state franchise regulatory agencies that have these on file as a matter of public record. Whether these will be the exact agreement at issue here is another story.
Franchise agreements generally say the franchisee is an independent contractor and responsible for its own employment matters. However the employer's handbook, based on what you've said, seems to go beyond this and could expose the franchisor to liability. I've been involved as a franchise expert in a number of these cases. You really should speak with an attorney in your area that has expertise in these matters.
Best of luck,
Kevin B. Murphy, B.S., M.B.A., J.D.
Franchise Attorney & Franchise Expert
Director of Operations - Mr. Franchise
FRANCHISE FOUNDATIONS APC