“Does everyone who dies become a ghost?” asks a just-orphaned Mary Lennox early in The Secret Garden, not realizing that the real ghosts at Misselthwaite Manor are her living, breathing relatives. In this Victorian postcard of a musical based on the children’s novel by Frances Hodgson Burnett, Mary (Rita Glynn) arrives at the secluded Yorkshire estate from India after the death of her parents in a cholera epidemic, only to find her hunchbacked Uncle Archibald (John Scherer) still grieving for his wife, Lily (Peggy Yates), who died in childbirth a decade earlier. Lily left her bereaved husband a hypochondriacal son, Colin (Justin Spencer Pereira), memories of having once been loved, and that titular walled garden. Archibald couldn’t bring himself to get out and smell the roses, so he discarded the garden’s key, and for 10 years, he has mourned as Colin has lain in bed. Mary is far too spunky to settle for so quiet an existence, so she teams up with the estate’s gardener (Harry A. Winter), his ebullient assistant (Stephen Gregory Smith), and a maid (Sherri L. Edelen) to search for the long-forgotten garden and bring it back to life. In the process, of course, she brings the household back to life, too. In Marsha Norman’s libretto, there are lots of spirits flitting around (Lily’s, as well as those of Mary’s parents) watching over everyone and offering advice—which isn’t as confusing as it sounds. There are also subplots (Archibald’s brother once had a crush on Lily, and he’s now the doctor who’s sedating Colin) that probably seem less labyrinthine in the novel. When the show played the Kennedy Center a while back, it looked frilly as a valentine and felt decorative and slight. John Going’s briskly businesslike production at Olney Theatre Center takes a darker approach. Scott Pinkney’s lighting verges on the spooky (perhaps because Daniel Conway’s design scheme creates its Victorian interiors and eerie moors mostly with projections that would be washed out if the illumination were brighter). The music is well-sung (albeit overmiked) and comes across as pleasant, if not particularly memorable or affecting—which could also be said of the performances. As a holiday alternative for families who’ve seen a few too many Nutcrackers and Christmas Carols, The Secret Garden will certainly serve, but it won’t strike most adults as much more than an attractively mounted, urgently performed piece of nostalgia. —Bob Mondello