故事围绕着五位主角展开。单身的泰德(乔什·拉德诺 Josh Radnor 饰)还在寻寻觅觅自己的真命天女,经历了多次失败的感情之后,他发现自己不再如以前一样有信念了。意外重逢了6年前的女友维多利亚。他想和维多利亚复合,却被告知对方将要订婚 。 另一方面,马修(杰森·席格尔 Jason Segel 饰)和莉莉(艾丽森·汉妮根 Alyson Hannigan 饰)惊喜发现莉莉怀孕了,这个新生命让他们既开心又紧张。巴尼(尼尔·帕特里克·哈里斯 Neil Patrick Harris 饰)则忙于挽回前女友诺拉,诺拉决定再给巴尼一次机会,于是他们重新在一起。罗宾(寇碧·史莫德斯 Cobie Smulders 饰)醋意大发,她发现自己还爱着巴尼…… 本剧以“老妈”是谁为最大悬念,只知道泰德在巴尼的婚礼上遇见这位神秘的真命天女,她究竟是谁?It's moments before Barney's wedding. He's got the jitters over whether he picked the right woman for his bride, and as a result whether the wedding will be a disaster. Ted and Barney reminisce about Ted's friend Punchy's recent wedding, which they declare was the worst wedding ever. There were several possible lead ups to the disaster of Punchy's wedding. One possible cause might have been Ted feeling insecure both about his non-married status compared to all his high school friends in attendance, and them waiting for the screw-up that was supposed to be Ted's toast. His past toasts were now legendary because of video posts by Punchy on the Internet. Another possible cause of the disaster might have been Barney trying to test his pick-up plays on unsuspecting women at the reception, while he lied about a series of telephone calls he made. And yet another possible cause might have been what Robin decided about telling or not telling Barney that she still had feelings for him. But Ted admits that the disaster was Marshall's doing. Lily had just learned that she was pregnant. Lily didn't want them to tell anybody until she reached the end of her first trimester, and as such she made Marshall drink all her drinks that evening. An extremely drunk Marshall was apt to do anything to cause a disaster. But perhaps it was an innocent misinterpreted finger point that caused the mess.