Harley, a retired military service dog, is starting a new life with the Lacey family, but when he arrives, he discovers he has a new sibling; a tiny, bushy tailed, tri-coloured cat called Lucy. Will the local developers' plans to tear down the Old Ashley Place marshlands to build condos on unite the two? Can they settle their differences in time to save the marshland... and can cats and dogs ever become true friends?