In the Gloaming (Sunday (20), 9-10 p.m., HBO) Filmed in Westchester County, N.Y., by Frederick Zollo Prods. in association with HBO NYC Prods. Executive producers, Frederick Zollo, Nicholas Paleologos, Michael Fuchs; producer, Nellie Nugiel; co-producer, Bonnie Timmermann; director, Christopher Reeve; writer, Will Scheffer; based on the short story by Alice Elliott Dark; camera, Fred Elmes; editor, David Ray; production designer, Andy Jackness; costume designer, Jane Greenwood; music, Dave Grusin; title song, Dana Morosini; casting, Timmermann. Cast: Glenn Close, Bridget Fonda, David Strathairn, Whoopi Goldberg, Robert Sean Leonard. In the Gloaming” is certainly among the most movingly acted , sensitively wrought films centering on a mother-son relationship ever made. And the primary credit must fall squarely onto the shoulders of Christopher Reeve, who as its director took the short story from which the film was adapted and spun an hour of pure magic. HBO’s trust in Reeve to deliver a first-rate product was clearly justified: “In the Gloaming” confirms that the man’s physical limitations do not extend to his ability to tell a wrenching story of love lost and found. And, of course, it also doesn’t hurt to have Glenn Close at your disposal. Scripted by Will Scheffer from a 1993 New Yorker short story by Alice Elliott Dark, “In the Gloaming” tells the tale of a young gay man, Danny (marvelous work from Robert Sean Leonard), who is stricken with AIDS and comes home to live out his last days. The film’s early scenario takes its cue from “Ordinary People.” Danny returns to find the same icy-cool, upper-crust suburban home he left, and we meet family members emotionally hamstrung by denial and detachment. On the surface, they are the very essence of well-heeled splendor. Underneath, they can hardly breathe. Danny’s father (David Strathairn) is a middle-aged businessman who’s clueless as to how to relate to his son. His sister, Anne (Bridget Fonda), is an empty pool of yuppie angst. And mother Janet (Close) yearns for something more than the stifling existence that has become her life. Live-in nurse Myrna (Whoopi Goldberg, barely seen onscreen) completes the painful picture. Little changes after Danny comes home. Everyone more or less ignores his terminal condition; he reaches out to his mother to bring some level of meaning and closeness to a relationship long strained by misunderstanding. The scenes in which Close and Leonard’s characters bridge a vast emotional gulf through reminiscence and ironic humor are a revelation. An intimacy exists between the performers that transcends the material, their chemistry quietly exploding off the screen. Close is strikingly passionate or unguarded, while Leonard is superb in capturing the complex layers of Danny’s ever-evolving emotional state. “In the Gloaming” is rare in its utter lack of contrived sentiment, even when Danny’s near death. Credit a sparkling adaptation from New York playwright Scheffer. Tech credits are all superior, the location filming in a picturesque area of Westchester County supplying a luminous counterpoint to the disheartening story. The message of this film speaks to the resilience of the human spirit, a subject that director Reeve surely knows a thing or two about. May he direct often. We will all be the better for it.