By the time the fifth season of “The Handmaid’s Tale” rolls around, Serena Joy Waterford (Yvonne Strahovski) is already in dire straits. Still stuck in a detention facility in Canada, she has lost most of her allies, as well as her power and status in Gilead. But it’s after she learns that her husband, Fred (Joseph Fiennes), has been murdered that her world truly comes crashing down, as she’s left to fend for herself and her unborn child, in a foreign country and with the lingering fear that her former handmaid June (Elisabeth Moss) — who, alongside a group of other erstwhile handmaids, is responsible for Fred’s murder — could come for her next. While the grieving, desperate widow summons June to the battlefield in an act of retaliation, her main goal going forward, Strahovski argues, is to keep her head above water.

“I always think that survival is...