If a play’s success can be measured by the amount of meat it offers you to chew on, and the length of time it takes for you to digest it, then “That Good Night” can be considered a success.

For the first act, at least.

A totally dysfunctional family, the O’Dwyers, have returned to their childhood home in suburban Illinois to help their mother with her decision to pull the plug on their father, who has been hospitalized and in a coma for the past eight months.

The oldest son, Chuck (John Cragen), has left his wife and kids (one with A.D.D. and another with bulimia) and brought his current girlfriend, Louise (Keelia Flinn) home with him.

The second son, Danny (Chet Grissom), and his wife Gretchen (Melissa Kite) are Buddhists who have just adopted two Korean boys.

The youngest son, Sean (a magical Bernie Zilinskas), is a 37-year-old drug-addicted clown who still lives at home with their mother.

And finally, there is Alice, her father’s favorite, who does her best to ameliorate all the anger and dissonance between the brothers and to support her beleaguered mother.

Judith Scarpone plays the smugly sanctimonious mother, Millicent O’Dwyer, with pious intensity, humor and platitudes. She is uniquely wonderful. “By faith we walk with him, not by sight,” she repeats to her skeptical children.

“God has turned dad into his pet rock,” Sean says. And, “art is salvation.”

Chuck, defensive in the face of his siblings’ hostility, loudly declares, “Success is not a disease!” And he attacks his sister Alice by accusing her of trying to “make shit smell sweet.”

Gretchen, who acknowledges that her marriage to Danny is not as ardent as it once was, asserts that what they have lost in passion they have made up for in increased intimacy, honesty and forgiveness. Her marriage, she says, is good. Which doesn’t explain why she is flirting with Sean.

Left unexplored is a “fictional” short story published in an obscure journal in which Alice has revealed family secrets that are both shocking and scandalous. What those might be is not disclosed.

With the second act, however, the play becomes as dysfunctional as the family. The father, Jim (Leon Russom), has come out of his coma — whether before or after his family pulled the plug is undetermined. He is home, however, spewing vitriol and malice on everyone in sight — with the exception of the young Louise, for whom he makes a lecherous grab.

He is a thoroughly despicable man and a keen illustration of where all the anger and bitterness in his family comes from.

Director Scott Alan Smith has coaxed first-rate performances from each of the actors, but in spite of his best efforts, he is left to work with an impenetrably mushy second act.

Playwright Andrew Dolan has failed to pull together all the dangling pieces. In the end, Millicent, the pious wife and mother, snaps and attacks her husband with his own cane. Sean, who had claimed that he was impotent, emerges after a get-together with Louise with a gigantic, cucumber-sized erection. There is a pregnancy, a death and a funeral.

And we still never learn what was in Alice’s outrageous story!

“That Good Night,” whose title comes from Dylan Thomas’ elegiac poem (“Do not go gentle into that good night, rage, rage against the dying of the light”), is a world premiere production of The Road Theater Co. It will continue its run at the Lankershim Arts Center, 5108 Lankershim Blvd., in North Hollywood Fridays and Saturdays at 8 p.m. and Sundays at 2 p.m. through Aug. 4. Call (866) 811-4111 for tickets.

Cynthia Citron can be reached at ccitron@socal.rr.com.