The ‘Gossip Girl’ star is begging fans to find out if they’re a bone marrow match for one year old Ayelet.

"It's a classic demonstration of the power of the situation," says Ayelet Fishbach, a behavioural scientist at the University of Chicago, Illinois.

Ayelet Zurer (" Munich ") also is on board the production, playing Langdon's sidekick, a woman who is trying to uncover the mystery of her father's murder.