In Sacramento, Lu Ho is a stellar med student. When she falls critically ill, she gets a surprise visit from Gabriel, an old love who’d vanished mysteriously. Now he shares an app with Lu that lets her time travel and discover history did not unfold as she thought. When Congress bans Chinese women’s immigration, Lu must convince her ancestor, a doctor, to smuggle his wife into the U.S. and open a badly needed clinic. Lu seals the deal, saving countless lives for generations. But Lu’s illness takes a turn and she finds she must stare down her own mortality.