The Senior Partner where Ken works is retiring and he is hopeful that he is in line for promotion. Ben has an idea to try and spice things up with Rachel after she informs him that he needs to be more spontaneous.
When Ken and Lorna collect their daughter Rachel from the airport, they're horrified to learn that she's returned from her gap year with more than just a henna tattoo and braids in her hair.
At the arrival gate, she promptly introduces them to her new husband, Cuckoo - the squared-jawed, self-appointed "spiritual ninja" who is now their son-in-law. Cuckoo is every parent's worst nightmare - a slacker full of outlandish, New Age ideas.
Ken and Lorna have no choice but to welcome him into their family home - and if every Englishman's home is his castle, then this hippie has stormed Ken's fortress and plundered everything, most unforgivably, his princess.