Read on Kindle; print version is maybe 800 pages.
Story is written in first half of 19th century but the action is set in the 17th century. I read that it is considered a masterpiece and the first modern Italian novel.
I liked it a lot.
Renzo and Lucia (local peasants, poor though Renzo is a valued silkworker) are engaged to be married, but the local priest (Don Abbondio) puts them off after a warning from some local toughs (known as bravi - a sort of henchmen for those who do activities requiring henchmen). In this case, a squirrelly noble named Don Rodrigo wanted to have Lucia in some way, and headed off the marriage. The story goes on from there as Renzo and Lucia - seldom in the same location - try to evade Don Rodrigo and work through various other challenges.
The plague scenes are pretty compelling and certainly correlate to some Covid events. The Capuchins are presented as incredibly helpful. Fra Cristoforo helping Renzo and Lucia; they forgive Don Rodrigo.
Cardinal Federigo Borromeo, Archbishop of Milan, is helpful. The local priest is too scared to do his job.
Here's Gemini's summary -
Set in 17th-century Lombardy under Spanish rule, Alessandro Manzoni’s The Betrothed (I Promessi Sposi) is a cornerstone of Italian literature. The story follows two silk-weavers, Renzo and Lucia, whose plans to marry are thwarted by the local tyrant, Don Rodrigo, who desires Lucia for himself. Rodrigo intimidates the cowardly priest, Don Abbondio, into refusing the ceremony, forcing the couple to flee their village.
The narrative splits as the lovers endure a series of historical calamities. Renzo travels to Milan, where he becomes caught up in bread riots and is nearly arrested, while Lucia seeks refuge in a convent, only to be betrayed by the tragic Nun of Monza and kidnapped by the powerful "Unnamed." However, Lucia’s piety sparks a miraculous moral conversion in her captor, who eventually releases her.
Their trials culminate during the devastating Great Plague of Milan (1630). After surviving the disease, Renzo finds Lucia in a plague hospital (lazzaretto). With the help of the saintly Fra Cristoforo, who releases Lucia from a vow of celibacy she made in captivity, the couple is finally reunited. The novel concludes with their marriage, symbolizing the triumph of "Divine Providence" and the resilience of the humble against the corruption of the powerful.