Portwenn's only doctor continues to challenge the community, his wife and even Buddy, a stray dog, who cannot resist Doctor Ellingham's fervent rebuffs. Having separated for a breather in Spain visiting her mother, Louisa has returned, but not into the arms of Doc Martin. Insisting on a break while they try and sort out their differences, Louisa moves into the family home and Doc Martin moves out. In an effort to win her back, he agrees to undertake couples therapy with Dr Rachel Timoney - something that Louisa finds almost as challenging as he does. Life in Portwenn continues around them as Al Large tries to set up a new business while his father Bert decides to move away from an old one; Aunt Ruth faces a health issue which cannot be ignored much as she'd like to; and Morwenna has found a new flatmate who catches the eye of PC Penhale. But at the heart of it all lies the question - will Martin and Louisa's marriage be saved by therapy? And will Buddy make their house his home?