Cave Canem is the third book of the Felidae series, published in Germany in 1999.
The book introduces the recurring character of Junior, it's also notable to face important moral themes as the horror of the war and the mistrust and misunderstanding between different beings.
Cave Canem has several links with the Yugoslavian Wars and criticism to the massacres committed as implied criticism on the aerial bombing by NATO forces and use of depleted uranium weapons.
The book has yet to be translated in English, but a French edition of the book is available.
The story begins with Francis ready to make a visit to a pretty she-cat named Roxy to mate with her. Before departing he talks with Bluebeard and his friend reminds him about some mysterious cat deaths in the city (Francis is unsure of calling them "murders" because according him the victims could have been killed in accidents and unrelated events). After having a meal with his friend, Bluebeard also informs Francis that the Council lead by Moses asked his advice about the killings and that one last victim was found. Going to see the victim, as suggested by Bluebeard, Francis discovers it was Roxy that was killed.
Francis and Bluebeard reach the Council and are greeted by Moses and Sissi (a female pug, that acts as leader of the city's dogs). The dogs and cats accuse each other for the killings and Bluebeard manages to get their attention so Francis can speak. He explains how he's beginning to think that the victims may have been killed by an external enemy. Among the ranks of the dogs, rises Hector, an old ex-police dog with experience in crime and investigation. He gets assigned to work together with Francis on the investigation although Francis dislikes the idea of working with a dog and the whole feelings of that troubled day bring him to suddenly leave the Council under the watchful eyes of everyone.
Wandering away, Francis finds a new large dog pound in the suburbs, so large that it resemble a concentration camp according him. Driven by curiosity, Francis try to enter through a ventilation tube, but then he finds the body of a murdered guard dog and on the dog's identification tag he found the words "Cave Canem". Suddenly Francis realizes that other alive guard dogs (which are displaying horribly mutated bodies, as if they are infected or malformed) were going to catch him from behind and that he's trapped between them and the body. Another dog crushes the duct above him and grabs Francis, but luckily he realizes that it is Hector who had been sent to find Francis. Despite the friendly manner of the ex-police dog, again Francis refuse to collaborate with him, stressing the different nature of a detective and a police dog.
After reaching his home, Francis realizes that he acted unfair with Hector but the night is late and he's ready for a well-deserved sleep. Soon, he notices an unexpected presence is already asleep in the Gustav's bed. A smaller and younger cat that has the same pelt of features as himself!
Francis is so tired that he falls asleep rather then questioning the stranger about his presence, and during the night Francis has one of his nightmares full of meaning: a beautiful garden that is soon turned into a mass of human graves. When he wakes up and he's greeted by the stranger cat, Francis realizes that Gustav had believed the stranger to be Francis and so let him sleep in the bed. The cat confessed to being one of the Francis's sons, conceived a year earlier and in search of his father after the loss of his mother and siblings. The young cat is at first angry with Francis for having never had a father, but then he accepts to remain with Francis for now (and to tell him his name, Junior). Francis returns to focus on the investigation: he manages to use Archie's PC and surfing on internet he finds out that "Cave Canem" was a UN program for an elite team of dogs used in the Peacekeeping missions of the United Nations after the Yugoslavian Wars and among their task was to find mass graves by smell. Francis decides to make a visit to the house of General August Horch, the human commander of the "Cave Canem" group. After reaching his large villa, he find new proof that links the dog pound with the Cave Canem project but Francis wonders how the healthy dogs in the photos are linked with the transfigured and weakened monsters that hunted him there. The guard dog suddenly hears a noise accidentally made by Francis and chases him. Trying to escape, the detective falls directly into the aquarium of the General: an aquarium full of Piranha.
Hector appears and save Francis's life for the second time and then reveals more about his past, something that Francis was starting to realize on his own: Hector wasn't an ex- police dog but one of the war dogs from Cave Canem. He was not affected in the mind as the dogs that chased Francis in the pound, but still he carries a heavy memory of the sight of the mass graves and the horror of the war. Hector, however, firmly denies a possible involvement with one or more of his ex comrades in the killings.
Hector suggests to pay a visit to Andromeda, a gray, old, sick poodle who lives alone that, inherited a skill for astrology from her former master. But when they reach Andromeda, a group of five cats is attacking her with their leader being Junior himself. Francis manages to drive them away, and after having lectured Junior about his actions Francis tells him to never return. Finally talking with her, Andromeda falls into a trance-like state and despite Francis believing it was a waste of time, he realizes how there is something true in the prophecies of Andromeda. She begins telling them about the wars and massacres and Francis realizes how the killings are linked with what he defines as "the spirit of war" rather then a single and legitimate purpose.
Suddenly, Bluebeard comes rushing in reeking of fear, telling them that Sissi has been assassinated and the communities of dogs and cats were almost at war.
Francis and Hector run to where dogs and cats were ready to start a bloody battle and in an effort to stop them, Francis makes an incredible (and false) admission. He claims to be the murderer on the ground of a crazy plan to see how the two species could be driven to fight to death. This put an end to the imminent battle but now the leaders (Moses and the new dogs' leaders, Hinz and Kunz) chase him bringing the whole crowd with them.
Francis, while being chased by dogs and cats demanding his death, manages to jump on a car's roof and luckily the car stops in front of Francis's home and he realizes that the man driving the car was actually Archie.
After having reached the safety of his house (even if sieged by hundreds of dogs and cats), Archie falls asleep and Francis uses the man's PC. Francis has a suspicion that the true murderer could be linked with the article he had read about the Cave Canem project. He decides that whoever wrote the article may have important clues about the murderer.
Francis sends an email to the writer of the article (who was identified only as "Neptune") and took care not to reveal being a cat but signing himself as Archie and claiming to be simply interested into the Cave Canem project's history and the experiences of the group.
Our hero has to wait only seconds to receive a very short reply:
" Hello, dear Francis! I thought you'd never talk with me .."
Francis has a talk on email with this mysterious person, not knowing if he's talking to a human or an animal but after mysterious words, Neptune reveals how there is a "monster of the war" behind all this and gives Francis an address.
An unexpected help come also from Junior: Francis's son has returned to Gustav's home and facing his father he apologizes for his behavior and asks to be forgiven. Francis is happy to reconcile with his son and Junior manage to lure away the animals rallied out the house thanks the aesthetic similarity with his father.
Francis manages to find the location that Neptune told him to check, and he finds that it was the same abandoned villa of Andromeda. Inside this place, Francis find the Andromeda's body: she has been killed in the same way of all the other victims, with a perfect and clean wound on the neck that could be caused (by the size) both by a big cat or a small/medium size dog. Checking the wound, Francis realize how it could have been caused by an artificial craft to imitate an animal's bite. Also on Andromeda's belly was attached a photo, showing a ship on sea. The name's ship is visible: the Gloria, Francis remember to have seen a small model of the same ship while visiting the General Horches's home. Studying the photo, Francis recognize the same General dressed as the God Neptun during the party on the deck.
Hector reach Francis and tells his friend how he never doubted of the cat detective: he has managed to persuade Junior of being a friend of his father and as soon as he got the location that Francis was running to, Hector reached him.
Hector doesn't want to believe that the General is the murderer, because they lives together and Hector trusts him as a kind lover of animals. They return to Francis's home for one last test: checking the IP address of "Neptune" and the location of his computer: but the search show only the unexpected result of the same Archie's computer.
Finally after collecting all the clues, Francis realizes how the killer is actually an human; not the General, but his gardener: and ex- scientist and ex-fellow in arms of the General named Amöbius Mars (even if the perfect weapons for the murderers is recognized, a garden tool that could imitate both cats and dogs fang's marks)
Francis realizes how the purpose of the man was the same that he had claimed to have in front of the gathering of cats and dogs: forcing the two species to fight with the only aim of study and enjoy a war.
Francis and Hector rush to find him, running under the rain, and when they confront the man, they're surprised to find him perfectly aware of the animal's intelligence and even willing to speak to them (even if the man could not understand the animal's words).
Mars tells at Francis and Hector his past and his shock while being in military, and how now his only purpose is to enjoy the full spirit of a terrible war that he wants to cause between dogs and cats of the city.
Hector suddenly try to attack the man, only to be stabbed to death by him. Francis remain close to his friend, regretting to have show prejudices on him: he try to attack the man only to be crushed against the wall and having three ribs broken, while Mars declares his victory (having reached the abyss of madness) and believe Francis to be dead, the cat manage to survive.
Francis will be healed by a very worried Gustav and the animal revenge will not be late: after Francis will speak with Moses about what exactly happened, the cat will organize a crowd of other felines to invade during the night the house of Mars: causing a painful death of asphyxia enormous amount of allergens released from the hair of many cats in a confined space.