When Tash French's potty grandmother mistakes a Christmas cracker engagement ring for the genuine article, a wedding of astronomical proportions is planned. Swept away by everyone's enthusiasm, Tash and her partner, Niall, can do little but laugh and go along with it. After all, they had meant to marry all along, hadn't they?

As the wedding plans escalate, however, Tash starts to have doubts. Niall, a rising acting star, is always working away from home, forgetting important dates and falling in love with his leading ladies, and her own eyes keep wandering to a roguish fellow event rider. Even if the Best Man wins, Tash looks likely to give away more than her hand in marriage - she may lose her head and heart as well ...