The Son centers on Peter (Hugh Jackman), whose hectic life with his infant and new partner Beth (Vanessa Kirby) is upended when his ex-wife Kate (Laura Dern) appears with their son, who is now a teenager. The young man has been missing from school for months and is troubled, distant, and angry.

Peter strives to take care of Nicholas as he would have liked his own father to have taken care of him while juggling work, his and Beth's new son, and the offer of his dream position in Washington. However, by reaching for the past to correct its mistakes, he loses sight of how to hold onto the Nicholas in the present.