Riley is not thrilled when Bonnie promotes her to Maid of Honor and demands a crazy bachelorette party, while Brad asks Danny to be his best man and throw an epic, yet dignified, bachelor party. Tucker tells everyone he's going to a television convention in Detroit, but he's actually making his annual trek to Vegas, where he spends one weekend a year living his dream of being a lounge singer. When the boys discover where Tucker really is, they decide to move Brad's bachelor party to the desert, which, of course, means Bonnie and Riley are right on their heels. When they accidentally discover Tucker's act, everyone agrees to enjoy their own nights, but things get very interesting when Bonnie ends up handcuffed to illusionist Peter Oliver. Meanwhile, Danny finally admits to Ben that he's in love with Riley.

Baby Daddy follows Ben, a young man in his early 20s living the life of a bachelor in New York City with his buddy, Tucker, and his brother, Danny. Their lives are turned upside down when they come home one day to find a baby girl left on the doorstep by an ex-girlfriend of Ben's. After much deliberation, Ben decides to raise the baby with the help of his friends and his protective and sometimes over-bearing mother, Bonnie, and his close female friend, Riley.