In a poignant tale of serendipity and heartbreak, "At First Sight" follows the fateful encounter between a man and a woman whose lives intertwine in a single, life-altering moment. Drawn together by an inexplicable force, they experience love at first sight, only to have their bond tragically severed by a sudden accident moments later. Before being drawn apart, they are granted a brief glimpse into an alternate reality, where they explore the depths of their connection and envision the future they could have shared.

30 years after the events of The Brothers McMullen, romantic entanglements plague a now fiftysomething Barry McMullen and his twentysomething kids, as well as his brother Patrick and widowed sister-in-law Molly, who are also facing similar unexpected hurdles.