The film opens with 54-year-old Ben Kalmen (Michael Douglas), a very successful car dealer in the New York area, at his annual medical check-up; his doctor tells him he needs a CAT scan to get a better look at his heart, due to an "irregularity" in his EKG.

He is taking oral medications but never got the prescribed heart tests, and his lost sense of "immortality" has sent him on a self-destructive binge: habitual lying, illicit sexual affairs, divorce, and bad business decisions that nearly put him in prison.

Ben is broke, borrowing money from his daughter Susan (Jenna Fischer), still unwilling to accept his age, ignoring his heart problem, and has a serial sexual appetite.

Back in New York, Ben expresses a desire to continue the relationship, which Allyson dismisses as a one time experiment with an older man, in her words, crossing "the Daddy" fantasy off her "list".

While discussing his overdue rent with his building manager (Lenny Venito), Susan appears and tells him he is no longer welcome in her family's life, citing the affair with Allyson and his unreliability as a grandfather of her son.

The website's critics consensus reads: "Built around a singularly unpleasant main character, Solitary Man needed a flawless central performance to succeed -- and Michael Douglas delivers.