In San Francisco, Artie goes to the Museum of Art and meets with the curator, Mr. Logan, to examine the recreation of the tomb of an ancient pharaoh, Ho Tem Ra. Mounted on the statue of the pharaoh is a large ruby. They’re expecting Jim and the Egyptian representative, Heisel, to be there anytime. A guard delivers a shipment and Logan doesn’t remember expecting one, but tells the guard to bring it in. He admits to Artie that he’s been getting absent-minded in his old age. As Logan shows Artie a rare scarab, three men in gas masks emerge from the crate.
Jim and Heisel arrive at the museum and the guards let them through. When they enter the exhibit room, they find Artie and Logan unconscious. The intruders attack them and quickly gas them unconscious. Jim manages to pull the mask off of one of them as he falls, and as the man puts it on Jim gets a brief glimpse of the statue of Ho Tem Ra... now missing its precious ruby.
Later at the Wanderer
, government representative Finley offers apologizes to Heisel and Princess Miasmin. Heisel isn’t satisfied, reminding Finley that the U.S. government offered full security. When he suggests that Miasmin has become fatigued, she tells Heisel to go on ahead. Miasmin then assures them that Heisel can become emotional and informs Jim that before she left Egypt, a wedding date was set between her and a prince. If the ruby is now part of the dowry, the prince’s father the Khan will oppose the wedding and prevent peace between their two nations. Jim assures her that they’ll recover the ruby.
Once Miasmin leaves, Finley demands to know how they will find the ruby. Artie opens a window and inadvertently sets off an alarm, and Finley tells them to recover the ruby in 48 hours. As Finley leaves, Artie notices a package at the door. The agents open it and find one of the gas masks inside. There is also a note demanding $50,000 in return for the ruby. The agents are to take it to the Blue Whale Bar on the waterfront.
That night, a man with a jeweled dagger watches Jim go into the bar. Inside, a woman named Rosie is belly dancing for the sailors. Artie is also there, disguised as a sea captain. The bartender is expecting Jim and leads him to a corner of the bar. A voice speaks from a mask on the wall and the man at the other end, Jason Starr, tells Jim to pull the drape back. Heisel is in the next room, bound and gagged. Jason sends one of his associates, Ferret, to check for counterfeit money. Ferret discovers that the case is empty and Jim says that the money is nearby and his associate has it.
Jason agrees to show Jim the ruby but warns that he’ll kill Heisel if there are anymore tricks. Jason tells Jim to look at the prettiest thing in the room and directs his attention to Rosie’s toe. She’s wearing the ruby on her toe, but before Jim can do anything, someone throws a knife into Ferret’s back. A fight breaks out and Jim dives into the backroom to rescue Heisel. Artie fights his way past the sailors and goes after Rosie as she runs out. She loses Artie in the darkness and ducks into an ice factory.
At the saloon, the police haul away the sailors while Heisel thanks Jim for saving him. The agent admits that he didn’t recover the ruby and Heisel flies into a rage. He gets hold of himself and follows Jim’s advice to go back to his hotel. Artie returns and tells Jim that he lost Rosie. Jim shows him the jeweled dagger that was used to kill Ferret and Artie identifies it as belonging to an ancient Egyptian sect of palace guards. His partner has also found a key sewn into Ferret’s coat but neither one of them knows where it came from. Jim has Artie trace the dagger while he looks for the girl.
Rosie goes to her apartment and starts packing, and finds Jason and his men waiting for her. He tells her to hand over the ruby.
Artie checks out a local coffee shop, Port Said, but the waiter refuse to let him in, claiming that they’re full. Artie flashes the jeweled dagger and the owner, Amalek Kassin, comes out and apologizes for his waiter’s poor manners. He invites Artie to join him at his private table and the agent accepts, and Amalek soon asks about the dagger. Artie lets him examine it and Amalek has the waiter bring him liquor from his private stock. He then offers to buy the dagger but Artie angrily refuses, saying that he’s fond of it. Amalek secretly drugs Artie’s drink but the agent notices. He distracts Amalek with a magic trick and dumps the glass into a nearby urn, and then “swallows” the liquor. Artie then walks away, leaving a puzzled Amalek.
Jim finds Rosie’s apartment and discovers that someone has torn it apart.
Out on the street, Artie spots two of Amalek’s men following him. They grab him and lead him to a dead-end alley and through a secret panel. Amalek is waiting and throws the mate of the jeweled dagger into the wall next to Artie. One of Amalek’s men take the dagger and the Egyptian demands to know who Artie is and why he’s been flashing it around town. Artie says that he has the ruby that goes with the knife and Amalek starts to threaten him. There’s a knock from a screened-off corner and Amalek holds a whispered conversation with the man behind the screen. Amalek then offers Artie $50,000 for the ruby but wants it within three hours or else. Artie agrees and leaves.
Jim searches until he finds the Star Warehouse, which matches the star on Ferret’s key. He knocks out a guard and slips in. Jason is interrogating Rosie about the location of the ruby. She refuses to talk and Jason figures that Rosie is angry over Ferret’s death. The man was like a father to her, and Rosie blames Jason for his death. Jason brings over a case containing a tarantula and Rosie says that the ruby fell off her foot when she ran. He doesn’t believe her and opens the case, repeating his question. As the tarantula crawls toward Rosie, Jason notices the open window that Jim came through. The agent swings down, grabs a gun, and trains it on Jason. One of Jason’s men trains a shotgun on Jim, but Jim says that he’ll leave with Rosie in return for sparing Jason’s life. Jason agrees
Back at the Wanderer
, Rosie tells the agents that she was telling the truth about losing the ruby. As far as she’s concerned, the ruby can remain lost because it’s brought misfortune wherever it goes. Artie suggests that she take a nap and recover and the agents leave her alone. They go back to the main car and both figure that Rosie is lying. Artie tells his partner about Amalek’s offer and tells Jim that the ruby wasn’t worth more than $2,000. The agents wonder if Jason wants to blackmail the Egyptian government and why the ruby is worth $50,000. As they talk, the intruder alarm goes off and they figure Rosie has escaped.
Rosie goes to the ice factory and searches for the ruby among the ice blocks where she hid it earlier. Jim comes in and points out the ruby, frozen in a block of ice. He chips it free but Jason and h is men come in and take the ruby at gunpoint. Jim jumps the thugs but Jason punches him unconscious and his men toss Jim and Rosie into a freezing chamber. However, as Jason follows his men outside, someone kills him.
Jim wakes up and lights a lamp, and quickly realizes that the room is airtight.
Artie goes back to Port Said and Amalek’s men tell him to wait until their boss returns. They’re gambling and are glad to have Artie sit in once the agent claims he’s never played.
Jim uses a hidden explosive to try and blast the door open, but discovers that there’s not enough oxygen for a safe fuse. He shortens the fuse to a few inches, lights it, and dives away just in time. Outside they find Jason’s corpse and Jim tells Rosie that he knows who did it... and that Artie is in trouble if he’s right.
Artie cleans up in the game just as Amalek comes in and tells him that his luck has run out. He asks for the ruby but Artie claims that he can get a better offer from Amalek’s boss. Amalek denies it and has his men search Artie for the ruby. They give it to Amalek, who has the real ruby, but Artie says that he’s missing a golden opportunity that has been waiting for three thousand years. Amalek tells him that he’ll carry that secret to the grave and leaves while his men tie up Artie and prepare to apply a hot poker. Artie kicks them back momentarily, while outside, Jim finds the secret panel and comes in. He takes out the thugs and frees Artie, who says he knows where Amalek is going and that they have a half hour to get there.
At the museum, Amalek and his boss enter the main chamber and go to the statue of Ho Tem Ra. As they place the ruby back in the statue, Jim and Artie arrive and arrest Amalek and... Heisel. The agents already know that when the moon is in a particular position once every twelve years, it reveals a vast hidden treasure. Artie tells them that he can turn the clock back, puts the ruby in the statue, and uses mirrors to duplicate the path the beam took a few minutes ago. When Heisel says that moonlight will be too weak, Artie explains that he can use a parabolic mirror to amplify the light. Once he does so, the beam from the ruby focuses on a nearby obelisk. Heisel runs to the obelisk and tries to open it, but a final booby trap kills him while gold and jewels pour out of the obelisk.
Later, the agents return from giving Miasmin the jewel and find another package waiting for them. Inside is a present from Miasmin: a diamond. The agents realize that they can’t keep it just as the alarm goes off. They search the train and find Rosie in the adjacent car. She claims to get back her things and invites them to search her, but Jim says it isn’t necessary. Rosie thanks them for saving her life and they ask what she’ll do. She admits that she’d like to be a seamstress but no one will hire her given her past as a saloon girl. The agents take pity on her and give her the diamond so that she can open a shop. She accepts their offer but insists on trading them the pewter candlesticks she was stealing.