The pharaoh's mistress "Anck Su-Namun" was privy to pharaoh alone and not to be touch by anyone. However, she defied that situation for her love of Imhotep Egyptian High Priest. When discovered they kill Pharaoh Seti I ( Aharon Ipalé ). Here is where we cannot quite tell if they are staging the scene in order to kill pharaoh or if it happened due to a surprise encounter of discovery by him. Either way, she then kills herself in order to avoid punishment.
Killing herself was done out of faith that Imhotep being high priest could conjure her up from the grave with some ancient Egyptian ritual magic of some sort. Stealing her body for the ritual, Imhotep flees deep into the desert to Hamunaptra in order to resurrect her. It never occurred to them what the pharaonic guards would do when they found out? Surely they would miss her corpse and discover the situation. Apparently Imhotep loved her quite a lot, because he risked angering the gods by attempting the ritual deep in the city Hamunaptra and possibly disturbing the black book of Anubis for the ritual. Here is where he nearly completes the ritual before being caught by pharaoh's body guards who thwarted the ritual.
Condemning Imhotep and his priests, Imhotep was to endure an ancient curse so horrible it had never before been bestowed. He was to remain sealed in his sarcophagus and could not be released, for he would arise a walking disease, a plague, a walking flesh eater. Along with interesting features he would be restore with such as the power over the sands and invincibility. Which makes one wonder why risk such possibility?
Flash forward to some desert war in Egypt during the recent past. In which, Richard O'Connell ( Brendan Fraser ) is fighting in. Where the men fighting have little insight into what lies beneath. Rick is fighting some natives in what appears to be the French army. He only escapes when he stumbles upon Imhotep's burial site causing the natives to run out of fear. Later to be captured while meandering his way to safety (which is not shown in the film).
In a museum of old artifacts and books of study on the subject, Evelyn Carnahan ( Rachel Weisz ) "accidentally" knocks all of the book shelves in the library down with the books in them. Her brother ( Jonathan Carnahan - played by John Hannah ) surprises her with and ancient discovered item he had found in Thebes. The discovery happens to be the key to Imhotep's sarcophagus, which they discuss with the museum curator. Linking the item to Hamunaptra via a map inside, they set forth to find the city. The curator tries to discourage them to no avail, warning them that many have wasted their lives foolishly in pursuit of the city. All of which sounds suspiciously like the lost city of gold in Aztec/Mayan Myth.
Deciding against the curator, Evelyn and her brother go to Egypt anyway. Finding Rick captured in some Egyptian prison, they attempt to get him out. As it turns out her brother did not find the key/box in Thebes, but retrieved it from Rick. Offering the prison master 25 percent of the findings from Hamunaptra, they escape. Rick seems way too uncooperative while in a foreign prison which is why they were going to hang him.
Taking a boat toward their destination, they find they are not alone. Some Americans are, also, on their way there. The descendants of pharaoh's body guards as well find the ship and are interested in preventing the discovery of Imhotep. They break into Evelyn's room and attempt to steal the map and key. During a shooting match the boat sinks, and they must travel via camel the rest of the way. A few antics provide Evelyn and Rick an escape as well as a little assistance from the Americans.
Evelyn, having studied the place quite well, directs the digging to Imhotep's sarcophagus. Out gunned by the Americans, they demand rights to the site. So, they start digging else ware and stumble upon a sarcophagus for the man without a name. It happens to be the sarcophagus which requires the key they had from before. Using the key, but not opening the sarcophagus they return to their camp site. The pharaoh's body guards arrive where they demand that they leave in one day.
During a night of drinking wine, Evelyn pretends to know when to say when, then she drinks some more wine. Hence she gets too drunk. Rick asks her a few pointed questions, like why she is where she is. While he understands the other members of her family, he's not quite sure of her. As such seems to be revealing how out of place she is.
Returning to the sarcophagus of he without a name, Evelyn and crew open it. The body inside is still moist, decomposing and was apparently buried alive. Meanwhile, the Americans find "the Book of Anubis". Evelyn and Rick discover the scarab flesh eaters placed in the tomb upon the cursing of Imhotep as well as determine the curse he was condemned with. Sneaking the book of Anubis from the Americans, Evelyn opens it with her key then proceeds to read from it. The action of which immediately wakes Imhotep as well as some mysterious natural effects such as millions of scarabs.
Supposedly he will bring with him the ten plagues of Egypt. Escaping, Rick and the Americans plan on leaving Egypt. Evelyn refuses out of determination to stay and fight Imhotep. All the while Imhotep is meandering around the tomb with the objective of finding those that opened the casket to the "Black Book of Anubis" for a lunch time snack. He comes across Beni Gabor (Kevin J. O'Connor ) a little weasel of a character who was with Rick in the beginning. Here Beni tries to use religious charms to protect himself. Eventually revealing a Jewish star, Imhotep interprets that as the language of slaves and enlists him as a grunt.
The plagues of Egypt begin to ravage modern Egypt (or the not too distant past). Rick and crew plot to find a way to stop Imhotep before he fully regenerates into an unstoppable large immortal scary priest. Such an idea threatens all the inhabitants of Egypt and the world, striking terror into the involved parties as well as all of the neighboring rulers. The success of which would make Imhotep the largest scariest priest ever, who can wield the forces of nature. Once regenerated, he should easily conquer the nations of the world and install a puppet ruler. The likelihood that any neighboring nation with an army overcoming this might seems very slim at such a point.
Our friends discover that Imhotep will fear "cats" until he is fully regenerated. Determining the "Black Book of Anubis" would bring him back to life, the "Gold Book of Amun-Ra" would have what was required to return him to death. Meanwhile, Imhotep has enlisted mobs of Egyptians as seemingly mindless slaves in his quest to consume the flesh of those that opened the casket to "the Black Book of Anubis". Once he consumes their flesh he will fully regenerate.
Rick and crew embark to retrieve the "Gold Book of Amun-Ra". Imhotep arrives fully regenerated and takes Evelyn with him. Which they allow with the slogan, Live today fight tomorrow. Imhotep plans to complete the ritual of ancient times using Evelyn as a host to return "Anck Su-Namun" from the dead. With that intent, he returns to Hamunaptra with her. Rick enlists Captain Winston Havlock (Bernard Fox ) who has a British Royal Air Plane in order to attempt to catch them in Hamunaptra. Here is when the fight by Rick seems futile, but of course he already knows that stabilizing himself with a "Live today, fight tomorrow" attitude.
Both parties arrive at Hamunaptra, one knowing exactly what he is doing while the other simply trying to see what is possible to do about the situation. While digging their way through a doorway Jonathan discovers what appears to be scarab jewels in the wall. Removing one he soon learns it is living when it crawls beneath his skin as its nature to mummify him. Acting quickly Rick uses a pocket knife to cut through the surface skin and remove it. The act made easier by the fact that it primarily crawled along just under the skins surface. Curiously, why primarily the surface? It seems to have a plan to attack a specific artery, and crawls along the surface until it get close. Of course, that is what makes it an interesting special effect.
Finding the statue of Horus, Rick attempts to retrieve the "Gold Book of Amun-Ra". Meanwhile, Imhotep is attempting to complete the ritual with Evelyn as a host. Attempting to bring assistance their way Jonathan reads something from the "Book of Amun-Ra", because he has difficulty reading hieroglyphs it takes him a while to complete the inscription. Finally getting the key to open the book, Evelyn reads an inscription from the book which removes Imhotep's spirit from him returning him to mortality. At which point Rick kills him, causing the ancient Egyptian treasure room to sink beneath the sand where it is hidden again.
Particularly amazing is that simply reading a hieroglyphic inscription from the book of Amun-Ra would return him to mortality. As well as that they could actually do that. Why didn't they simply do that in the beginning and rescue themselves the torment? Ah, but of course it wouldn't be a movie then. Unfortunately they leave without a single bit of ancient treasure, but Rick gets Evelyn as well as a happy ending.