Aisling Bea does her best in And Mrs, a tonally uneven comedy about a woman determined to marry her dead fiancé, but even she can't breathe life into a clumsy script.

After kissing Nathan (Colin Hanks) goodbye as she heads out for her morning yoga, Londoner Gemma (Bea) returns later in the morning to find him still in bed, cold, having apparently suffered an embolism.

Though shell-shocked with grief, she must break the news of Nathan's passing to his sister Audrey (Billie Lourd), flying in from America, and, as it turns out, pregnant, a surrogate for a gay couple.

Supported by her almost-sister-in-law, Gemma resolves to proceed with the wedding to express her devotion to Nathan, greatly against the wishes of her best friend Ruth (Susan Wokoma) and mother Lorraine (Sinead Cusack).

Despite there being legal precedent for the couple to marry, harking back to the Napoleonic War, she and Audrey must persuade the chief justice (Harriet Walter) of the merits of their case. This involves them flying to the US to obtain the blessing of Audrey's estranged mom Margaret (Elizabeth McGovern), with Audrey also kicking off a viral social media campaign, #corpsebride.

Bea has written movingly in the past of her own loss and gives a sympathetic portrayal here of a woman sideswiped by pain, lingering guilt and regrets for a life that she will now never have.  She and Lourd, daughter of the late Carrie Fisher, share some touching moments, uniting in holding each other up, against the pressure of others towards their plan.

Yet director Daniel Reisinger isn't hugely concerned with exploring the psychological impact of Gemma's grief in any real depth. And the Irish comic is mostly forced into the role of straightwoman for the mercurial Audrey's disruptive behaviour, affording her fewer and fewer opportunities to display her comic chops as the story progresses.

In her screenwriting debut, playwright Melissa Bubnic also makes some baffling decisions. Gemma and Audrey infiltrate a hearing on sex work to try to get an audience with the chief justice, with the American browbeating a male police chief inspector to the approval of women present, before going too far, stinking out the room to little comic effect.

And for seemingly no other reason than he's Paul Kaye, the Dennis Pennis and Mike Strutter star pops up in a single scene conducting Nathan's funeral, toxically making it all about him.

Audrey's impending motherhood became a feature of the story after Lourd herself got pregnant. Yet neither Reisinger or Bubnic seem to know quite what to do about her bump, beyond the implication of her making rash decisions.

Acting in only his second film, Nish Kumar nails his part in the proposal scene. But then with each subsequent appearance, he's turned into a less and less sympathetic character, his intransigent insistence upon upholding pub quiz rules played for laughs but increasingly falling flat. The now almost ubiquitous Sunil Patel is solid, popping up as a well-meaning security guard, even if his initial, dialogue-free appearances make it feel as if some of his earlier scenes may have been cut.

The film's most reliable turn is Walter as the severe, unbending but not unsympathetic chief justice. McGovern is also chillily effective, conveying long-buried regret and hurt in her brief cameo, a comedy-free encounter.

Most problematic is the character of Ruth. Wokoma deftly traverses a tightrope of outwardly being a rock for Gemma while secretly plotting against the wedding, her friend's well-being paramount in her objectives. But that isn't enough for Bubnic, who also gives Ruth heartbreak, foregrounds her sex appeal and parachutes in Nathan's idiot pal (Arthur Darvill) from America as an unlikely romantic interest.

That contrivance is matched by Gemma's gay friend Mo (Omari Douglas) also being belatedly shunted towards a romantic situation, to retrofit the film's ultimate hope that love conquers all. 

All the while, a slightly wooden Hanks occasionally interjects from beyond the grave in Gemma’s imagination and in flashback, but perhaps seems justifiably content on the other side of the spirit plane.