In September 1995, Cathy Ostlere’s family gathered in Calgary to celebrate the 36th birthday of her younger brother David. The birthday boy himself wasn’t there, but that was hardly unusual: it had become a family tradition for David, stricken by wanderlust, to call home on his birthday from wherever he was in the world to touch base with his family and celebrate in absentia.

That year, however, David didn’t call, and only Cathy knew why. Weeks before, David had sworn his sister to secrecy: he and his girlfriend Sarah were planning a sailing trip from Ireland to Madeira and didn’t want to worry his parents. As the weeks went by without any word from David, however, Ostlere was eventually forced to divulge the secret. And when it was determined that David and Sarah were lost at sea, she was nearly overwhelmed by the guilt of maintaining her silence for as long as she did.

Those two threads – the disappearance of David and Sarah, and Ostlere’s emotional reaction to it – comprise Ostlere’s memoir. Ostlere explores the aftermath of a family’s tragedy with a startling emotional candour; Lost is much more By Grand Central Station I Sat Down and Wept than The Perfect Storm or The Godforsaken Sea.

This is problematic, however. By framing the story with the mystery of what happened to David and Sarah, Ostlere creates certain expectations. The intensely personal and often revelatory nature of the memoir, in particular the repercussions on her family, her marriage, and her soul, feels self-indulgent and out of place, a sense that is furthered by the often excessive quality of the writing. (“My hand goes to the window. A daughter’s fingers reaching for a thousand lights. Who is lost? And who will be found, on this chance of land?”) Too often one feels she is wallowing in her own emotional life and giving the disappearance, the ostensible subject of the book, short shrift.

There is certainly some fine writing in Lost, and Ostlere’s honesty and forthrightness are both hard-won and tremendously affecting, but the memoir’s construction results in a book that is substantially less than the sum of its parts.