It's the summer and everyone is excited, about to disperse on their vacations. Eliot however is stuck behind doing a show so he sends Ace and Rosie on a vacation, accompanied by Eddie and Dot.

Eliot kicks off a crash exercise course with Artie as his trainer so he can run with Terri in the Dog City marathon and learns that you can't get in shape overnight. Ace Hart gets his fair share of exercise at the Fido Olympics, as he tries to solve the mysterious disappearance of the athletes and ends up competing against Bugsy Vile! Mr. Moggie takes his turn at exercise in the time-honored tale of "The Tortoise and the Hare." And we are introduced to the Woof Pack superheroes - lead by the Watch Dog, and followed by Pectoral Pooch, Plastic Lassie, Wonder Whelp and Hear Boy!

Eliot and Artie help each other overcome their fear of the future. While Ace and Eddie chase Rottweilers most recently commissioned world domination device -- a doggie door time portal machine. Yves la Chance's ancestor carries on the family name as the greatest cat burglar in the cosmos - but Stevens great great grandson hasn't changed a bit. He still dresses in the same uniform and still foils Yves attempts at every comic turn. Rosie and Dot take a trip to a futuristic amusement park where Rosie demonstrates to Dot, with the help of the Vile gang, how crime will be cleaned up in the future.

Artie has every doggie in the building recycling, but not before he makes life miserable, especially for Eliot!Meanwhile, Ace Hart uncovers another plot by the Baron Bon Rottweiler to take over the world when all the trees in Dog City are tree napped. "Rosie and Dot" go camping beside the Bugsy Vile gang and Mad Dog pays homage to Argbor Day by reciting a poem, and another installment of Yves and Steven finds cat burglar's attempts to steal the prize possession, foiled by Steven.

Eliot helps Artie to understand that a hero doesn't have to be a superhero. Sometimes heroes are just ordinary dogs doing ordinary things, like his mom, Terri. Ace and Bugsy battle it out for the "Hero of the Year " award. Mr. Moogie saves the day by shrinking himself small enough to go into the stomach of the Presidog to fight a patch of bad grass. We also meet with the Woof Pack as they go rocketing off to the supermarket in search of biscuits.

Eliot salutes the horror genre in this chiller thriller, but strange things start happening in his own building as Artie, Bruno and Eliot begin to think that Bruiser has gone mad in a case of mistaken identity. Meanwhile Ace Hart and Eddie have stumbled onto a plot by Rottweiler to take over the world with his Sci - Fido monster and Rosie as it's bride! Mr. Moggie takes us on an adventure under the bed as he confronts and triumphs over "The Thing under the bed." Our Dog City cast also puts a slant on their version of the well-known Edgar Allan Poe-em, "The Tell Tale Heart, Liver and Egg."

Eliot shows Artie that learning can be fun after Terri voices her concern over Artie's poor math grade. Meanwhile, Ace Hart tries to solve a case involving Bernie, the big pink star of the wildly popular kiddy show and discovers it's the Vile gang. We also meet Bugsy vile in "His Master's Choice Theater" as he reads to us a twisted version of Aesop's fable. We also learn about proper puppy behavior in "Good Doggie, Bad Doggie, " where Ace Hart & Mad Dog demonstrate the fine points of puppy etiquette. And finally Mr. Moogie learns about math by diving into a blackboard and tackling multiplication.

Ace Hart adventures in Jurassic Bark complete with the Bugsy Vile gang, while Eliot helps Artie grapple with the trials and tribulations of creativity. We also meet new characters for this season such as Yves'n Steven-Yves, a cat burglar whose attempts at stealing the guarded prized possession are always foiled by Steven, the happy go lucky guard dog. We get an introduction to Dot, Rosie's niece in the adventures of "Rosie and Dot." Finally we meet Mr. Moogie, Artie's animated squeaky toy.