Amelia Peabody, a plain-spoken, fiercely independent Englishwoman of thirty-two, narrates the story. The youngest of six children, she spent her youth managing the household of her scholarly, reclusive father and studying languages and antiquities alongside him. When he dies, she inherits his entire fortune of half a million pounds, shocking her older brothers and drawing fortune hunters. Uninterested in marriage, Amelia decides to travel abroad to see the ancient sites her father studied. She engages a companion, Miss Pritchett, but Miss Pritchett falls ill with typhoid in Rome, leaving Amelia alone.
While visiting the Roman Forum, Amelia finds a young Englishwoman collapsed on the ground. She brings the girl to her hotel and offers her a position as companion. The girl, Evelyn Barton-Forbes, insists on confessing her past first: She is the granddaughter of the Earl of Ellesmere, who raised her as his favorite. Her cousin Lucas Hayes, son of the Earl's disowned daughter who married an Italian count, is the male heir. An Italian drawing master named Alberto seduced Evelyn into an elopement, then abandoned her when he learned the Earl had disinherited her after a stroke. Amelia responds not with horror but with a blunt question about whether the physical experience of love was pleasant. Evelyn bursts out laughing, and the two form an immediate bond.
They sail to Cairo, hiring a dragoman (guide and interpreter) named Michael Bedawee and booking a
dahabeeyah, a flat-bottomed Nile houseboat called the
Philae. Amelia develops a passion for Egyptian antiquities. At the Boulaq Museum, she provokes a furious argument with Radcliffe Emerson, an English archaeologist, by picking up a statuette to dust it. His younger brother Walter, a philologist, apologizes and is immediately drawn to Evelyn. That evening, Evelyn spots Alberto across the hotel lounge and faints. He comes to their room demanding she return to him; Evelyn refuses, and Amelia drives him off with her parasol. That night, a figure in ancient Egyptian costume appears at Amelia's bedside and vanishes, leaving behind a small faience (glazed ceramic) amulet.
Before they depart, Evelyn's cousin Lucas arrives. Now the new Earl of Ellesmere following their grandfather's death, he reports that the old Earl recovered briefly, gathered all of Evelyn's belongings, and sent them to her before dying. Lucas proposes marriage. Evelyn refuses, and Lucas vows to follow them up the Nile.
The
Philae sails south toward Tell el-Amarna, the ruined city of the heretic pharaoh Khuenaten (now known as Akhenaten), who abandoned Egypt's traditional gods to worship the sun disc, Aten. The Emersons are excavating there. They arrive to find Walter desperate: Emerson is gravely ill with fever, and there is no doctor for hundreds of miles. Amelia takes command. She and Evelyn nurse him through a violent crisis, forcing quinine down his throat while he thrashes. During the coma that follows, Emerson seizes Amelia's hand and will not let go. She kneels beside him through the night until the fever breaks before dawn.
Amelia decides to stay until Emerson recovers, setting up camp in nearby tombs. His major discovery is a brilliantly preserved painted pavement from Khuenaten's royal palace, depicting birds, flowers, and animals. Amelia takes over the painstaking preservation work while Evelyn paints a watercolor copy. A newly discovered tomb yields a mummy in a rough coffin. Mohammed, the villager who found it, claims it is a cursed priest of Amon, a traditional Egyptian god, but Emerson identifies it as a much later burial.
The mummy soon vanishes, and strange events follow. Amelia sees a pale, bandaged figure outside the tomb one night; Evelyn sees the same apparition the next. Mohammed spreads word that the mummy walks at night, cursing anyone who disturbs the heretic city, and the village workers refuse to return. The painted pavement is smashed to fragments overnight, destroying weeks of work. Attempts to trap the mummy fail. Walter and the foreman Abdullah watch the village and confirm Mohammed never left, proving someone else is the impersonator.
Lucas catches up and joins the camp. A rockfall traps Amelia and Emerson inside Khuenaten's remote royal tomb. An elaborate trap, with Evelyn as bait and Lucas armed with a pistol, goes wrong. Lucas fires at the mummy, but it keeps coming despite apparent hits. Walter leaps to intercept it, and Lucas's next shot strikes Walter in the shoulder. The mummy retreats, howling with laughter. Emerson notes the creature is too tall to be any of the villagers. Michael has also vanished from camp, leaving only his gold crucifix with its chain snapped, evidence of abduction.
Suspecting Evelyn is the mummy's true target, Emerson sends her and Amelia to the
dahabeeyah overnight. Lucas dines aboard and stays the night. The mummy appears on deck, strikes Lucas down with some invisible force, and flees. The crew reports sleeping unnaturally, as if drugged. Back at camp, a cobra is found on Amelia's bed; Emerson kills it with the last bullet in the revolver.
Evelyn, believing she brings disaster on everyone, announces she will marry Lucas and leave. The deadlock breaks when Amelia blurts out to Walter that Evelyn loves him. Walter rushes to Evelyn; she confesses her full history, and he accepts her completely. They are engaged. Lucas accepts the loss with apparent grace, toasting the couple with wine.
That night, Amelia and Emerson realize the wine was laced with laudanum, an opium-based sedative. Fighting its effects, they find Michael crawling toward camp, badly wounded; he has been a prisoner since his disappearance. Evelyn's screams pierce the night: The mummy clutches her unconscious body on the ledge, then leaps and flees. Lucas gives chase, but gunshots soon pin Amelia and Emerson in their tomb. The sniper is Lucas, who has doubled back.
Trapped together, they assemble the full picture. Emerson reveals that Lucas's
dahabeeyah arrived near Amarna the same day as Amelia's, not weeks later as he claimed. Amelia supplies the motive: The dying Earl likely wrote a holograph (handwritten) will restoring Evelyn's inheritance and hid it among the belongings sent to her. Lucas, whose real name is Luigi, is Alberto's cousin. Together they orchestrated the mummy charade to obtain or destroy that will. When marriage to Evelyn became impossible, Lucas resorted to abduction. Emerson kisses Amelia. They escape and, with help from Abdullah, overpower and bind Lucas.
At the royal tomb, they find Alberto, who has been the mummy all along, boasting to the bound Evelyn. Emerson subdues him. Walter is found nearby, tied up but alive. They sail for Cairo with their prisoners.
On the voyage, Emerson avoids Amelia for two days. She corners him and proposes a "business proposition": She will fund his excavations if he allows her to participate. He confesses he has loved her since she walked into his tomb and started ordering everyone about. They agree to marry.
Writing from Amarna two years later, Amelia reports that she and Emerson are excavating together and expecting their first child. Walter and Evelyn are married with an infant son; Evelyn's boxes contained the Earl's holograph will restoring her inheritance. Lucas has fled to the Continent in disgrace, and Alberto is in an Egyptian prison. Amelia closes by affirming that Evelyn was right about love: Under the right circumstances, it is "perfectly splendid."