As the Antareans prepare for their long-awaited return to their home planet after an extended five-year mission on Earth, they face the crucial task of retrieving the cocoons they abandoned during a previous rescue effort. However, one of these valuable cargo pieces is intercepted by scientists who whisk it away to a secure laboratory for thorough inspection. Now, the aliens, aided by their human friends, must formulate a plan to infiltrate the facility and reclaim the cocoon before time runs out. Simultaneously, they grapple with a significant dilemma: should they remain on Earth or head back to Antarea?
In this emotional landscape, Joe, portrayed by Jack Gilford, confronts the painful reality of his leukemia returning. Yet, he knows that upon leaving Earth, the disease will cease to be a threat. Tragedy strikes the group when Alma, played by Maureen Stapleton, courageously saves a child but gets hit by a car in the process. In a heart-wrenching demonstration of sacrificial love, Joe relinquishes his remaining vitality to save her, ultimately leading to his own demise. Before he passes, he shares poignant advice with Alma, encouraging her to take up a position at a preschool while expressing his deep feelings for her.
As the story unfolds, Art and Bess discover they are expecting a child, prompting them to decide to raise their family on Antarea, embracing the chance to see their offspring thrive. Meanwhile, Ben reconnects with Mary, including their friend Bernie, who has found new love with Ruby, helping him cope with the emotional scars left by Rose's death. Jack, still nursing a broken heart, endeavors to win Kitty's affection again but is instead met with a mystical vision of his future, featuring children, a loving spouse, and a heart-shaped birthmark adorning her neck.
On the brink of leaving for Antarea, Alma announces her choice to stay behind and commit herself to teaching at the preschool. Just as the group is adjusting to the idea of departing without her, they are called to action by Kitty, who needs their help to rescue an imprisoned Antarean from the Oceanographic Institute. Sara, a compassionate scientist at the facility, becomes aware of the malicious schemes to turn the alien over to the military and, understanding their plight, aids them in executing their daring escape.
Amidst these transitions, the characters face their own intertwined fates, wrestling with the significant impacts their decisions will have on their lives as they move toward an uncertain future. When the quartet successfully retrieves the Antarean vessel from Jack's boat drifting in the sea, Ben reveals to his friends that he and Mary have chosen to stay on Earth, valuing familial connections over the allure of eternal life. This heartfelt admission is met with understanding and empathy from their companions, who recognize the importance of not outliving one’s children. The emotional separation is palpable as they bid farewell to their loved ones, aware that their choices will permanently alter the fabric of their relationships.
Meanwhile, Jack returns to the dock, sharing a poignant moment with Ben, Mary, and David before parting ways. He is drawn in by Sara's unexpected inquiry about fuel, leading them on a leisurely stroll filled with conversation. As they talk, Sara opens up about her recent choice to leave her job, voicing the uncertainty of her new chapter ahead. During this heartfelt exchange, Jack’s attention fixates on a small, heart-shaped birthmark on Sara's neck, hinting at the intricate layers of her character and the potential for further connections in this evolving narrative.
