In this sisterly PS, I Love You, an introverted young woman is saddled with fulfilling her late sister's final wish: completing her bucket list while millions of people follow along online.

Jodie Boyd is a shy and anxious twenty-something, completely unsure of what to do with her life. Meanwhile, her older sister, Bree, is an adventurous, globe-trotting Instagram influencer. Bree is the most alive person Jodie knows - until her unfathomable, untimely death from leukaemia. The Boyds are devastated, not to mention overwhelmed with medical debt. But Bree had a plan, and to Jodie's surprise a new post appears on her sister's Instagram feed.

The first of many posts Bree recorded in secret, it contains a jaw-dropping challenge for Jodie: complete Bree's bucket list. From 'fly over Antarctica' to 'fall in love', if Jodie pulls it off, a corporate sponsor will pay off the crushing medical debt.

It's crazy. It's terrifying. It's impossible to refuse . . .