Guardian of the Horizon

The story begins in summer, 1907, ten years after the Emersons' expedition into the Nubian desert in The Last Camel Died at Noon, when the Emersons were lured to a Lost Oasis, the home of a Meroitic - Ancient Egyptian civilization that had survived for centuries without contact outside itself. They went to find Mr Forth, as requested by Tarek who went to England to find the Emersons. They learned Mr Forth had died, and brought his daughter Nefret Forth to live with them in England, as he wished for his daughter. A messenger from the Lost Oasis appears at their home in Kent, pleading for help for their friend, King Tarek. They go to his aid, though they mistrust the man who claims to be Tarek's younger half-brother.

Ramses experiences the feeling of foreboding that normally assails Amelia, as they head off to the Sudan and into the desert to help their friend. Unlike their first trip, they bring a larger force, including Selim and Daoud, in full awareness that the Lost Oasis is no longer a secret. The Emersons are not the only ones interested in it, and their current journey there is dogged by followers. These include a British adventurer Newbold who has in his company a young woman, Daria. Daria attempts to seduce Ramses, unsuccessfully, but he is attracted to her. He is really in love with Nefret, as he discussed with David before this trip was planned. On this trip, Amelia experiences the oasis near the City of the Holy Mountain fully, in its green and water-rich beauty; she had been ill on the first journey by that point, carried to safety by Tarek and his men.

Upon their arrival, they find that King Tarek has been deposed by Zekare, the father of the duplicitous Merasen who brought them back. Zekare's plan is to obtain the endorsement of the Emerson family to neutralise the popular resistance to his regime. Nefret is taken from the group and made to resume her position as high priestess, which she finds distasteful now. They notice changes, as there is now coffee to drink, paper on which to write, and hardened steel knives and swords. There is clearly a supplier importing these goods. This brings Sethos to their minds. When Amelia catches an intruder in their quarters, she is relieved to find that it is her enemy and admirer Sethos, disguised as archaeologist MacFerguson; he promises to rescue Nefret from all the women holding her in place.

A usual rite honoring Isis is the setting chosen by the usurper to assure his hold on the throne. A few days before that, Ramses escapes the family quarters to encounter Tarek and his men. He brings Daria with him, as he was able to take her away with no armed guards stopping him. Before the last part of the trek, the two make love, and then sleep. He then gives her to Tarek. Tarek plans to attack on that ritual day, his in-town supporters will rise up. The Emersons feel that the change can be accomplished without an uprising, a possible civil war, by a different approach. Tarek listens. One aspect of the different approach is getting Nefret away from the ritual, and Sethos gets her out when he is disguised as a priest, bringing her to the Emerson family quarters.

Emerson is active in these schemes, as he is seen as a god-like figure in this culture. He speaks to the public and negotiates with the usurper. Amelia comes up with new plans as events change rapidly. Selim and Daoud aid directly, and make friends with the servant class easily.

Leaving Tarek, descending a steep slope, Ramses is wounded, falls a long way down, and is imprisoned by the gleeful Merasen. Ramses shares his cell with Moroney, former English army captain who saved Merasen from those who captured him in the desert and led him back home, which good turns led Merasen to imprison him. Merasen brings Amelia to tend to her son’s wounds in prison; she left “women’s weapons” with him. Ramses immediately escapes the prison with the aid of Amineslo, an ally of Tarek sent by his mother, and the weapons, and they both escape. Ramses joins his family.

On the day, Emerson addresses those gathered outside City of the Holy Mountain, dramatically pulling out an arrow that hit his chest; in fact it hit the makeshift armored vest he and Amelia devised. Amelia and Nefret, dressed in their working clothes and not the gowns given them, appear at the temple. Merasen sits on the throne, and tells them he ordered his father killed, then killed his brothers who had done the job for him, one of those rapid changes that mark this visit. People are assembled for the ritual; Ramses enters as the advance guard for Tarek. Ramses and Merasen fight a duel with the new swords. Ramses defeats Merasen, but cannot kill him while he is down. Merasen makes a last move to kill Ramses. Merasen fails, as the bullet from Daoud's gun hits him in the chest, killing him. Emerson and Tarek enter the scene.

Tarek is again the king and the people are satisfied. He will take Daria as his wife, and she hopes to provide him with sons.

Sethos, still as MacFerguson, got a broken leg in the melee in the temple. Amelia tends to him and keeps Emerson from seeing him. Sethos tells her that he had been coming to the City of the Holy Mountain for eight years, and has a few precious items from the place. He explains that Daria is his agent, who followed Amelia on this trip.

Tarek arranges an odd meeting of Ramses with Nefret in her father’s tomb. Nefret is in a trance state, and repeats conversations she had with her father when he was alive. She promises him she will remain a maiden, not marry. Tarek knows that she could never marry him. Both Tarek and an old woman from the village make clear that Nefret will belong to Ramses. Thus far, Nefret sees him only as her brother, so this is challenging for 20-year-old Ramses to believe.

The Emersons with Selim and Daoud trek back to the oasis, on camels, having survived the summer trip in the desert.

Chronologically, this book covers the dig season of 1907-1908 immediately after The Ape Who Guards the Balance set in 1906-1907, although it was published some years later than the books that follow it chronologically.

Publishers Weekly found this novel, where the Emersons return to the Lost Oasis featured in The Last Camel Died at Noon ten years later, to be a good addition to the series. The overall judgment was that "Peters's knowledge of ancient Egypt ... in the region allow her to dress her melodrama with authentic trappings that add greatly to the enjoyment."[1]

Audio File magazine reviewed the audio book, narrated by Barbara Rosenblat. They praised her for her excellent work in conveying the story, noting that it won an Earphones Award. In a brief remark about the novel, their comment was "Kidnapping, murder, political intrigues, and damsels in distress make this sixteenth episode in the Peabody Chronicles every bit as exciting as the others."[2]

• List of characters in the Amelia Peabody series