The story picks up where Queste ended. Jenna, Nicko, Snorri, Ullr and Beetle are in the harbor known as the Trading Post, where Jenna encounters her father, Milo Banda, who persuades them to spend the night on his ship. Back in The Castle, Septimus gets a promotion to Senior Apprentice by Marcia Overstrand, for being the only apprentice wizard to complete the Queste. This enables him to head off on an adventure of his own. His escapade begins as he plans a simple flight on board his dragon, Spit Fyre, to retrieve his friends from the Trading Post.
Around this time, Aunt Zelda sends Wolf Boy from the Marram Marshes. She is giving him a challenging test for becoming the first male Keeper. As soon as Wolf Boy leaves, Zelda retrieves a SafeCharm, which appears to be a tiny, pear-shaped gold bottle. She needs to deliver it to Septimus, however, by the time she arrives he has already left. Due to an unfortunate mix-up, the SafeCharm falls into the hands of Merrin Meredith who stole it believing it to be a rare perfume. When he takes the top off to sniff it, a jinee comes out of it. "Jim Knee" as he is called by Merrin, sets off on his own adventure. Meanwhile, Wolf Boy bumps into Simon Heap in the Port; he was looking for his fiancee Lucy Gringe who had been missing. Wolf Boy approaches the House of the Port Witch Coven. There he reads Zelda's letter which tells him to feed a creature called Grim and cut-off its tentacle tip. The Port Witch takes him inside her kitchen and wakes the Grim, which is a giant octopus. The witches bring forth a captive Lucy to feed to the Grim. Under the pretense of feeding Lucy to the Grim, Wolf Boy and Lucy escape from the coven. They are chased by a senior witch, Linda, but they escape by riding straight into a leaving ship.
While flying towards the Trading Post, Septimus sees a bunch of seven islands on the sea and hears a voice calling him. Ignoring the voice, Septimus continues his journey and reaches Milo's ship The Cerys. There Milo shows Jenna a big trunk which is full of tiny lead tubes and which he declares to be brought specially for Jenna's safety. Jenna, getting tired of Milo's hospitality decides to leave the ship and fly off home with Septimus and Beetle on Spit Fyre. But while flying home, they get caught in a raging storm. They try to find the Cattrokk Light, a lighthouse in the middle of the ocean, and fall onto a nearby island when Spit Fyre's tail gets struck by lightning. Septimus tries his best to cure the tail with Physik but his attempts fail. He is also perplexed by a voice calling his name continuously. One day Septimus sees a girl approaching him. The girl introduces herself as Syrah Syara; Septimus remembers meeting her when he went back in time 500 years, during the events from Physik. She fled from The Castle during the Queste and hid on the island. Syrah heals Spit Fyre's tail and reveals that she is under a terrible enchantment by the resident evil ghost of the island known as Syren. The Syren, a singing ghost who attracts sailors by her voice and leads them to their doom by possessing them, stays in a tower atop the hills of the island. Syrah takes Septimus there to show him an opened ice-tunnel latch beneath the island; she mentions that danger is approaching the Castle. Before Septimus can close the ice-tunnel, the Syren takes hold of Syrah while Septimus flees.
Meanwhile Marcia goes to the Manuscriptorium vaults and finds that the ice tunnel latches, which pass from The Castle to the Seven Isles of Syren, through Cattrokk Light to the House of Foryx, are opened. Suspecting that the evil ghost Tertius Fume may be behind this, she returns to the Wizard Tower to find Zelda who informs Marcia about Septimus' danger. Together they find the jinnie and lock him in a sealed chamber in the Wizard Tower and devises a plan to help Septimus. Lucy and Wolf Boy continue their journey aboard the ship whose captain is a pirate. They reach Cattrokk light and there, the pirate's henchmen throw the lighthouse guard overboard. Lucy and Wolf Boy hide from them in one of the rooms of the Lighthouse. Surprisingly, they find that the lighthouse guard, Miarr, who is half-cat half-human, is still alive because cats have nine lives. The ship's captain and his henchmen take the light from the lighthouse and transport it to the island where Jenna and Beetle reside, and they see them coming. Miarr then leads Lucy and Wolf Boy to an underwater machine which allows them to approach the island unseen.
The Cerys travels towards The Castle under Nicko's steering. However, near Cattrokk Light, Nicko hears the Syren's song and believing mistakenly that the light on the island is coming from the lighthouse, he sails the ship onto the rocks. The pirate ship's captain and his henchmen then ambush Cerys' passengers, but Septimus and the others are able to lock them in the hold and save them all on board. The captain and his henchmen open the trunk, which contains thousands of bottles of jinnie and release them. To their horror, Septimus and the others find that the jinnie warriors come on board and address Tertius Fume as their master; he is on the island directing them towards the Syren tower ice tunnel. Meanwhile under Marcia's order, Septimus' jinnie finds him. Septimus and Beetle come to the conclusion that since Jim Knee was in a golden bottle, he has the power to overcome the warrior jinnie because gold is purer than lead. Septimus orders Jim Knee to go and freeze one of the warriors so that all the others will be simultaneously frozen. The front line of warriors had already reached through the ice-tunnel to the Wizard Tower, where just as they are about to kill Marcia under Fume's supervision, Jim Knee freezes the last jinnie; hence freezing all the other jinnie warriors. Marcia triumphs and informs a surprised Fume that she will see to it that his ghost is eradicated forever. Septimus and the others rejoice and Lucy and Wolf Boy help Miarr to put back the light atop Cattrokk. Septimus also orders Jim Knee to go and capture the Syren and force it into a small sealed bottle; hence Syrah is saved from her terrible enchantment. However, learning that more than 500 years have been passed since she arrived there and that Julius Pike is long dead, Syrah becomes comatose. The whole company returns to The Castle, where Marcia, Sarah and Silas Heap and Aunt Zelda meet them.
- Septimus Heap- protagonist of the story.
- Jenna Heap- accompanies him on the Syren Islands.
- Nicko Heap- Sails back aboard the Cerys and grounds it.
- Simon Heap- He tells Marcia about Skipper Fry being Tertius Fume's Bondsman.
- Syrah Syara- Possessed by the Syren, she tells Septimus about the plot and works with him to try to save the Castle.
- Syren- Possession Wraith, she struck a bargain with Tertius Fume that if he removed the lighthouse light, she would give him access to the Ice Tunnels.
- Tertius Fume- Planned to bring the army of Jinn through the Ice Tunnels to invade the Castle.
- Milo Banda- Transported the army of Jinn on his ship until it was grounded on the island.
- Skipper Fry- Fume's Bondsman, worked to carry out his plan.
- Snorri Snorrelsen- Northern trader girl, who was trapped into past along with Nicko. Now she is free, she wants to travel back to castle by Cerys.
- Lucy Gringe- Simons girlfriend, who was kidnapped by Witches of the Port. Wolfboy rescued her, but they only runned into bigger problems.
- Wolfboy- Boy who tries to become a Keeper. He saves Lucy Gringe and finds himself in middle of Tertius Fumes plot.
- Miarr Catt- Skipper Fry needed the light of CattRock and almost killed him.
- O. Beetle Beetle- Boy who accompanies Septimus and Jenna at Syren isle.
Terry Miller Shannon from Kidsreads.com said: "As we've come to expect from this series, 'Syren' offers gripping adventure, whimsical characters, a mesmerizing plot, derring-do heroics, and tons of delightful humor." Charlyn Trussel from Goodreads was impressed by the book and said "I nearly devoured the entire book the first weekend after I got it and then realized that it would be gone too soon and doled out the rest of the book through the week to be finished today. I recommend it for those who have made it through the rest of the series and still want more." Hilary Williamson from The Bookloon commented that "Angie Sage gives readers, pre-teen and up, non-stop action, a rich plot, and delightful details, as in Young Army sayings like 'Use Your Head or You Are Dead' and the amusingly uncooperative jinn Jim Knee. Septimus Heap fans will have great fun with this latest exciting adventure, Syren." Stefan Bagman from The Bookbag felt that "Syren is a fun, fun book and the best yet in the series. [...] This is a brilliant continuation of the series and definitely a must-read for anyone who has enjoyed the Septimus Heap books thus far. But again, don't start here if you are new to it all. Book one is almost as good." Sage's writing style was applaueded with Bagman saying that "[Sage's] writing is what makes the whole thing such a delight. It's just as good at conveying flat-out hilarious moments (like a genie-summoning scene towards the beginning) as it is with the tense and slightly creepy ones. She's also great with her characters, describing all of them, even the naughty ones, with a certain warmth and humaneness." Nannette Morges from Wilton Villager commended the maturity of the characters.
|World of Septimus Heap by Angie Sage|
|Septimus Heap novels|
|Magyk · Flyte · Physik · Queste · Syren · Darke · Fyre|
|Septimus Heap · Jenna Heap · Nicko Heap · Marcia Overstrand · Alther Mella · Silas Heap · Sarah Heap · Zelda Heap · Nicko Heap · Simon Heap · Lucy Gringe · DomDaniel · Merrin Meredith · O. Beetle Beetle · Spit Fyre · Alice Nettles · Snorri Snorrelssen · Ephaniah Grebe|
|The Darke Toad · The Magykal Papers|
|TodHunter Moon novels|
|PathFinder · SandRider · StarChaser|
|Alice "TodHunter" Moon · Ferdie Sarn · Oskar Sarn · Princess Driffa · Benhira-Benhara Grula-Grula|
|Colouring Book of Hours series|
|A Colouring Book of Hours: Castle|
|Magyk · The Castle · Wizard Tower · The Port · Marram Marshes · The Badlands|