Snake is possessive and private, hiding—he thinks—who he is from his club family. After being gently kicked out by his conservative family, Snake finds his path to his new family on his own. He feels like something is missing in his relationship with his secret lover, but is afraid to voice it for fear of losing Hawk.

Hawk is big, muscled, and a simple man. He enjoys his work with his MC, even if he hides his relationship and love for his partner, Snake. An event at the club allows them to be open and honest with their club family. Which opens his eyes to another possibility.

Oliver is a paralegal and a nerd to boot. He dreams of being in a triad relationship, a ménage, surrounded by love. But he finds it hard when he works all the time. A new door opens with a friendship in the legal world, and Oliver is excited, nervous, and afraid. Two men catch his eye, and when it becomes apparent they are interested in him as more than just an added partner for the night, Oliver is ready to take that offer with both hands.

Insecurities get the best of people with the best intentions, will communication ease fears or are they too deeply rooted?

Their Missing Piece is a part of the SOS Motorcycle Club's standalone universe.