At the Providence's next port of call, Tiger and Sinbad go ashore and the bounty hunter negotiates a lucrative transport deal with the Professor. The Professor pays a high price but warns them that she expects premium service for her money. She then shows them the cargo: a large black egg-shaped object some 7' tall.
That night, the crew loads the object into the ship and are forced to put it in the sleeping quarters because it won't fit in the hold. The Professor will be accompanying them to Tya Island and Tiger is confident that she can find the distant island. The bounty hunter assures them it's a simple assignment but Rina figures that the Professor is paying too much for it to be that simple. The Professor complains about their treatment of the object and insists that it's not a egg, but refuses to explain what it is. Sinbad tells Anwar to put the Professor up in his quarters while he sleeps in the main chamber with the others.
The Providence sets sail the next morning and Tiger expertly charts their course. Sinbad, impressed, asks her what she knows about the Land of the Dead. She refuses to discuss it until Sinbad tells her that he lost his brother and asks if she's lost anyone she cares about. Tiger tells him that she was raised by tigers after her father abandoned the girl-child that he despised on the rocks and that she never had anyone to care for.
As Anwar clears his things out of his cabin, the Professor sees his sketches of Rina and dismisses them. He tells her that he studied at the Basra Imperial College and the Professor haughtily tells him that her theories will change the world. When she wonders what he has done, Anwar examines the object and confirms that it's a vessel, not an egg. He wonders what it contains and the Professor says that it holds spores that can be used to fertilize the barren and uninhabited Tya Island. Once they arrive there, she will open the vessel and let the vegetation take over once more.
Sinbad takes some wine to Tiger's new spot on the ship and discovers that she's made a primitive den with blankets and a warning net. Tiger finds him and half-seriously threatens him with a knife, and he offers her some wine. She accepts and Sinbad asks if she can't help him or won't help him. Tiger admits that even if she could get him to the Land of the Dead, there are places that the living shouldn't go.
Once the Professor is alone in her new quarters, she removes a syringe from her case of medical supplies and uses it to extract blood from her arm. She then goes out and orders Rina to get her a gourd of water. As she goes to get it, she complains to Anwar and points out he's no longer the smartest person onboard. Rina, disagreeing, tells him that Tya Island is inhabited despite the Professor's claims and storms off.
The Professor quietly approaches the egg and injects her blood into it. Anwar comes over and she hastily puts the syringe away, and he asks her about the island. She ignores her question when she discovers that the egg is in direct sunlight, and tells the others to put it back in the shade. When the crew points out that there's no room, the Professor tells them to wash it with cold water every two hours or they'll be in breach of contract. Eager to collect the money, Tiger agrees and invites her to join them for their meal. The Professor complains that Cook uses too many nuts in the food and walks away.
Coo, offended by the Professor's comments on his cooking, prepares an elaborate meal but Anwar insists on taking it to her. She takes Anwar to her cabin and confirms that only Rina knows about Tya Island because there's a penitentiary there. The Professor admits that Rina is right but that she has made a deal with the primitive natives so she can perfect her experiment. She appeals to Anwar's intelligence, inviting him to witness her work at the end of the journey. He agrees and she asks him to keep her secret as one scientist to another.
A fly lands on the egg, and a crack opens in it and sucks the insect in.
That night, Anwar goes to the deck to take his turn at watch. Rina reminds him to water the egg and then goes to bed. The next morning, she wakes up and discovers that Anwar slept though his watch... and that the egg is now broken open up and empty. Anwar figures that the spores were destroyed but Sinbad insists on everyone searching. They hear something shrieking in the hold and Sinbad has Tiger and Rina keep the ship on course while he goes below with Anwar and Gunnar to deal with the spores before the Professor wakes up.
When they start exploring, the three men discover that something has eaten all of their food supplies. They also find a discarded snake skin, several feet long. The skin's owner, a large serpent, lunges out of the darkness and bites Gunnar on the arm. He manages to throw it off and they get up the ladder and seal the hatch behind them.
The Professor soon wakes up and snaps at them for losing her cargo. The crew demand to know what it is but the Professor is more interested in getting a description and examining the of the bite marks on Gunnar's arm. She tells them that it's fully formed and they realize that it must be nocturnal. Tiger gathers pans to reflect the sunlight from above while Gunnar starts weakening from the wound. As the others help him, the Professor tells Anwar that they need to work together to protect her creation. She explains that she bred the serpent to consume the plague-infested rats on Tya, but since it hatched prematurely its blood is to concentrated. The professor Anwar for his help thinning the creature's blood and he reluctantly agrees.
Anwar and the Professor open the hatch and she gives him a vial to release, thinning the creature's blood and rendering it harmless. They split up but the Professor then retreats up the ladder and seals the hatch. When Anwar realizes what is happening he yells for help and the serpent closes in on him. He throws a bag of food at it and it stops to swallow it whole. As the Professor hides, Sinbad and the others come down and open the hatch. Anwar climbs up and the serpent comes after him, but Tiger uses a pan to blind it momentarily, driving it back.
When Anwar finds the Professor, she grabs him by the neck and holds him hostage. She then orders Cook to open the hatch but the serpent grabs her arm and tries to pull her down. The others try to pull her free but fail until the serpent rips off her arm and retreats.
As the crew binds the Professor's wound, Anwar complains that the should have let the serpent take its creator. However, Sinbad points out that the Professor is the only one who knows what they're facing. Rina goes through the Professor's notes and discovers a reference to the professor she was working with. Anwar confirms that the professor believed that humanity is a flawed species because of its compassion and sought to create a serpent that would consume the weak of every species. According to the notes, the serpent will continue growing. They hear the serpent smashing through the hull and realizes that it will soon sink their ship.
Sinbad says that they have to abandon ship and the crew prepares to leave in the dinghy. However, Cook refuses to abandon the ship, believing that he should die with it since they are bound together by destiny. Sinbad insists that it isn't his friend's time but Cook refuses to move and the others decide to stay with their crewmate. The crew battens down the hatches and lowers a boom and fastens their cage to it. While Rina tends to the unconscious Professor, Tiger suggests that they use one of their own as bait. The crew member will stay in the cage until the snake grabs it and then the others will hoist it out using the boom. Sinbad volunteers and they go to work, unaware that the Professor has revived and managed to open one of the hatches. The snake grabs her and hauls her in and the crew realizes that once it feeds upon her it will grow even stronger.
As Sinbad prepares to enter the cage, he discovers that Tiger has already locked herself inside. She insists that she's best suited to handling the serpent if something goes wrong, and Sinbad reluctantly lowers her. Once the cage is lowered into the sleeping quarters, Tiger emerges to lure the serpent toward her. It rears up out of the cargo hold and the bounty hunter realizes that it has taken on the Professor's facial features. She bars the hatch and yells at the others to pull up the cage, and then hangs on as they pull it up. Once Tiger is safe, they reseal the hatch and she tells them what she saw. Anwar checks the Professor's case and confirms that she was injecting her blood into the egg. Now the serpent and the Professor have merged, joining her intelligence with its strength.
Cook gets an idea and figures that the hybrid may also share each individual's weaknesses. The snake starts to slam through the hull while Cook gets the nuts that he offered the Professor earlier. He tells the others that he has seen people that suffer from an allergic reaction when they eat nuts and figures that they can cause the serpent's throat to swell by feeding the nuts to it. While the others prepare torches, Cook makes a paste from the nuts and then spreads it on three crossbow bolts.
The serpent smashes through the hatch, flooding the hold, and Sinbad prepares to fire while the others hold it off with torches. Sinbad misses the first shot and the serpent goes underwater and then grabs Anwar. Gunnar manages to grab his friend and pull him free, and the serpent smashes into Sinbad, forcing him to drop the second bolt. The snake goes back underwater and the crew hack at the water until the serpent emerges, lunging at Sinbad. He shoots it in the neck and the serpent starts choking, giving Gunnar time to kill it with his axe.
The next morning, Cook finds a few eggs to serve since the serpent wouldn't eat them. As Sinbad and Tiger relax, she offers to lead him to a monastery on the island of Malta. It has a collection of maps and she believes that one of them could lead Sinbad to the Land of the Dead.