“Sometimes love speaks loudest as we let it go.”

Those words were part of Vanessa Redgrave’s concluding voiceover in May 3’s penultimate episode of Call the Midwife. After the May 10 finale, viewers who’ve followed this sterling British drama for all or part of its 15 seasons will have to let go of it in its current form, at least temporarily, as the series goes on hiatus. Expect an abundance of poignant moments.

“There’s a lot of endings,” says Rebecca Gethings, who has played nun and midwife Sister Veronica for four seasons. “It will be a very emotional episode. Not only is the show drawing to a close, at least for the time being, a lot of major storylines that we’ve seen running through the season are drawing to a close.”

Indeed, the impending closure of the maternity home marks the end of an era for Nonnatus House’s nuns and nurses, who care for the families of London’s working-class community of Poplar. As the season finishes up in 1971, expectant parents Rosalind and Cyril (Natalie Quarry and Zephryn Taitte) are set to tie the knot, even without her parents’ approval. Amid their celebration, the ailing Sister Monica Joan (90-year-old original cast member Judy Parfitt) prepares for what comes next, having already stopped her medication.

Judy Parfitt and Chris Reilly (Neal Street Productions/Olly Courtney)

Meanwhile, Sister Veronica, whose desire to become a mother sent her on a physical and spiritual journey that took her away from Poplar, has to decide if she’ll return to the order or continue her lay life. Going by her given name, Beryl, she’s been enjoying her stay with Geoffrey Franklin (Christopher Harper) — sleeping late, wearing fashionable clothes, and getting makeup tips from his sister Trixie (Helen George).

We’ll also see more of the Mullucks family. Parents Bernie and Rhoda (Chris Reilly and Liz White) were introduced in Season 5 when Rhoda gave birth to a daughter, Susan (Emily Webb), with severe limb defects because she’d been prescribed thalidomide while pregnant. With their elder daughter, Belinda (Rachel Andrews), now home from college — and pregnant — the family tries to come together to chart their future.

Look for a cameo appearance by a former cast member and lots of nostalgia as the show goes on hiatus before returning for Season 16. With a limited-series prequel, Sisters in Arms, set during World War II, slated for the holiday season and a film in the works, showrunner Heidi Thomas notes, “Love isn’t just the best medicine, it is medicine. That’s the philosophy that’s kept us going.”

Call the Midwife, Season 15 Finale, Sunday, May 10, 8/7c, PBS (check local listings at pbs.org)