When Penelope Magnificent’s awful parents tell her they’re taking a trip to Paris, she surprises them by begging to go along.

Nell is usually content to avoid her money-obsessed father and her fashion-focussed mother, but Paris holds something very dear to her… her old au pair Perrine - Pear - lives there. Pear used to write to Nell every week promising to come to her rescue but recently the letters have stopped…

Arriving at her parent’s posh hotel, Nell is determined to find Pear… but no one has seen her at her last known address, and no one seems to want to tell her anything about Pear’s whereabouts.

Luckily she befriends the hotel bellboy who introduces her to the world of tunnels underneath the city, and together they set out to find Pear, whilst uncovering an extraordinary mystery of their own…