Marley and Me: The Puppy Years is the sequel to the highly-acclaimed, Marley and Me.
Brodi Grogan (Travis Turner) has been hired to look after Marley (voiced by Grayson Russell) while her owners are working abroad for the summer. Marley is a puppy and very uncontrollable, wreaking havoc wherever he travels. Brodi would love a dog of his own but his mother, Carol (Chelah Horsdal), doesn't believe he is responsible enough.
Brodi goes to stay with his grandfather (Donnelly Rhodes) while his mother is at a conference. He is an ex-marine who runs a tight ship, declaring that Marley must be kept under control. However, Marley doesn't agree with the terms and procedes to chew his way through the entire house.
Frustrated with Marley's behaviour, Brodi takes him for a walk to run off his excess energy, meeting Kaycee (Sydney Imbeau) who is out walking her Pugs, The Barkinators. When Brodi explains his dilemma to Kaycee, she tells him about the neighbourhood puppy contest in which the puppies must do a series of obstacle courses.
Hoping to win so she can help with her family's animal shelter, Kaycee encourages Brodi to enter. She even tells him about Mrs. Crouch's (Merrilyn Gann) puppies, so Brodi would have the necessary three puppies to enter. Excited, Brodi acquires the additional puppies and builds an obstacle course in his grandfather's backyard.
The puppies Fuschia (Lauren Lavoie) and Moose (Ryan Grantham) join Marley in misadventures and mayhem and even foil the plot of Hans (Alex Zahara) and his attempts to disrupt the competition so that his miniature Doberman Pinscher puppies to win. Hans will stop at nothing in order to remain the champion, even using electronic devices to keep his puppies in order.
After many upsets, the competition begins and Brodi is left wondering if it was all worth the aggravation. He is positive he has failed and his mother will view him as irresponsible. Only Marley and the puppies are able to save the day but with their unpredictability, the outcome doesn't look good.