You can’t have a midlife crisis without some extreme behavior. But when Wallace Avery (Colin Firth) grows weary of being in an unhappy relationship, looking for work and becoming progressively disconnected from his son and ex-wife, he goes to drastic lengths to leave his former life behind him and start anew. So drastic, in fact, that he creates Arthur Newman, a retired golfer ready to settle into the next phase of his fictitious career as a golf instructor at a Terre Haute country club. So he stages his own death, buys a Mercedes and begins a cross-country trek destined for a truly new life.
Not long after he sets out on this journey, Arthur meets a troubled younger woman named Michaela (Emily Blunt). Clearly having a very different kind of identity crisis of her own, Mike (as she prefers to be called) inadvertently offers just the type of adventure Arthur didn’t even realize he was looking for. While doing a good deed, Arthur and Mike find themselves breaking into the home of a newlywed couple and taking on two additional personas. This role playing becomes such a thrill for Arthur and Mike that they continue fantasizing about being other people while having sex in the homes of these anonymous couples. As their bizarre methods of finding themselves continue, the two grow emotionally closer to one another as each learns more about the other.
While Arthur’s escape from reality is based on problems that are pretty typical of men of his age, Mike is running from things that are much harder to remedy. Having taken on the persona of hew twin sister, a paranoid schizophrenic currently locked away in a mental hospital, there’s more to Mike than Arthur probably wants to know. But he finds out soon enough when he wakes up one day to find that not only is Mike gone, but so is the bag of cash he’s been using to fund his trip. After Mike turns herself in, however, Arthur bails her out and they continue on their way. Seems like a stupid move on Arthur’s part until you remember that he’s a boring middle-aged man who’d probably like to continue having sex with this beautiful younger women, no matter how twisted the scenario might be. Plus, the fact that Mike, who he now knows is a kleptomaniac, felt some sort of regret after stealing his money indicates that maybe she’s changing for the better.
Just when it seems that Arthur and Mike’s fantasies are about to become reality, all of their lies are exposed, leaving them to sort through the shortcomings they’ve been trying to cover up. But they’ve discovered a good bit about themselves, thanks largely to their paths unexpectedly crossing. Realizing what they really need to do in order to find true happiness, they’re both able to find peace despite what would otherwise have seemed like a frivolous adventure.