Maggie Jackson's Odyssey is a tender, comic romance about the pathos and bathos of marriage, mortality, and growing old.

How well do married couples really know each other?

Psychotherapist Maggie would have said she was contented, if not happy, in her marriage until she found amorous text messages on her geriatric pop-philosopher husband Colin's phone. Taking his credit card from his wallet, she set off from their affluent home in Twickenham on a spontaneous odyssey across Europe, visiting their old haunts and brooding on her sense of betrayal and loss. But Maggie's libido was not as exhausted as she thought, and she too was susceptible to the seductive allure of a late-life dalliance.

Back home, she insisted Colin move out. A year of separation rekindled a libidinal passion between them, shot through with Maggie's rage and Colin's fumbling attempts at reconciliation. Now, lockdown has forced them together.

Maggie broods and reminiscences as she prepares for Colin's 71st birthday. Can she forgive him? Does she want to stay in their marriage? It's not as if she expects perfection: "Good enough is as much as we can hope for, and it helps if he keeps his dick in his trousers. It's not too much to ask, is it?"

Restless and irritable, in a day zinging with tension, she reflects on their relationship and on her solo jaunt around Europe: "It wasn't really a jaunt. What can I call it? A pilgrimage? An odyssey? Yes, an odyssey. Maggie Jackson's odyssey. That's what it was. Not exactly a Greek tragedy. Probably more of an Ealing comedy if the truth be told. Shirley Valentine meets Mrs Dalloway."

She mourns over her mother's mental decline, in a care home with dementia as Covid stalks the land and Prime Minister Boris Johnson tries to play Churchill. Maggie's Irish mother, Orla, was a beautiful, flamboyant extrovert who rid herself of several husbands before deciding to raise her three daughters alone. Now, Orla fantasises about her Hollywood lovers and wonders why Maggie has abandoned her.

Through it all, Maggie does her best to play the good wife: planning a Zoom party with the family; Skyping her mother several times; preparing a special birthday dinner a deux; gossiping with her best friend Barbara on the phone, and trying to suppress the guilt-inducing jibes directed at Colin that threaten to derail all her efforts. But as her alter ego keeps reminding her, Colin wasn't the only one to go astray.

They break lockdown rules and walk along the River Thames for a picnic lunch. Maggie feels herself softening towards Colin as they stroll together and splash through paths flooded by a high tide, on a sunny spring day: "The weather is glorious, as if some cosmic prankster is offering us sunshine, flowers and birdsong as consolation for isolation, suffocation and death." Then a revelation from Colin jolts her into a new reality. She realises that she hardly knows the man she has been with for nearly all her adult life. But then, Colin doesn't really know her either. How well do couples ever know each other?

The day ends with a raucous Zoom party, after which Maggie swims naked in the river and is astonished when Colin joins her. They eat in the summer house and dance on the lawn, as "the full moon of Holy Week casts a milky benediction on our sorrowing world."