Accidental Billionaire Plus-One

All I did was mail one of my sister's rejected wedding invitations to a stranger.
A notoriously private, famously grumpy billionaire stranger.
As a joke. Mostly. (I also sent one to Ryan Gosling. Don't ask.)
But then a helicopter nearly flattens the reception tent at my sister's Hamptons wedding, and out steps the billionaire—wearing a tux, a scowl, and carrying a gift.
What?
The bride’s side wants to know if he’s with the groom.
The groom’s side wants to know if he’s with the bride.
My sister absolutely cannot find out he’s here because of me!
So I intercept him and beg him to pretend he’s my plus-one.
And he says yes.
Not because he’s nice. The man lives alone on a yacht and reportedly hates everyone. He has his own reasons for wanting to fake-date a broke dance teacher—reasons he refuses to explain because he is the SURLIEST MAN ALIVE.
But four days of forced proximity is a long time.
Long enough to discover that beneath all that billionaire-grade hostility, he’s surprisingly good at protecting me when things fall apart.
The problem?
Fake dating him is starting to feel dangerously real.
And falling for the surliest man alive was definitely not part of the deal.