Jennifer Garner was chosen to play Hannah, and as a fan of the book herself, she was seriously excited to tackle the role. “I devoured the book,” Garner told Vanity Fair, admitting that she read it with one of her children. “We were so compelled to keep reading, and bedtime was just flying out the window every single night because it was just one more chapter, one more chapter, one more chapter.” Garner was chosen to replace Julia Roberts, who was initially cast as Hannah, after Roberts was forced to pull out over scheduling issues.

If the actor who plays Owen, Nikolaj Coster-Waldau, looks familiar to you, you’re not alone. He played perpetually confused Jaime Lannister on Game of Thrones, so this role as a husband and father who will “do anything for his daughter” seems pretty new to him. In a sense. But in a totally different sense, it’s the perfect fit. Coster-Waldau played a deeply loyal, protective character throughout Game of Thrones and yes, that relationship was perhaps less than healthy. But he’s great at giving off mysterious energy, and The Last Thing He Told Me gives him a chance to do something he loves — acting. “After Game Of Thrones, I was attracted to getting to do smaller things where it's just two people in a room talking so — and this sounds silly — I could just focus on the acting,” he told NME.

Fans of the excellent limited series Mare of Easttown will recognize Angourie Rice. She played Kate Winslet’s grieving daughter Siobhan Sheehan. Rice proved in that series that she can play a teenager who is at once vulnerable and strong, self-aware and frightened. In short, she was an excellent choice for Bailey, a teenager whose mother died mysteriously, whose father has gone missing, and who finds herself stuck with a stepmother she doesn’t really like. Also a gym bag stuffed with $600,000 left in her locker. When Rice was first offered the part last April, she posted a photo alongside a copy of The Last Thing He Told Me with the message, “beyond excited.” And so are we to see her in this role.

When Aisha Tyler was cast as Jules, Hannah’s best friend and a journalist who helps her to investigate Owen’s disappearance, the Criminal Minds star admitted it wasn’t a difficult role to play for her. Not least of which because she’s a person who loves “a puzzle,” she told TooFab. “I really hate when things get tied off perfectly, and what’s great about this show is it’s a mystery and it’s unfolding for the characters on the show at the same time as it’s unfolding for the audience," she explained, calling the series “a really fantastic, beautifully woven mystery that we all get to engage in on picking as an audience and it’s a blast to watch.” Playing Garner’s best friend felt pretty natural for her too. “Magically, Jen is just such a delight to be around that it didn’t take a lot to get to start pretending to be her best friend,” she told the outlet.

In the immediate aftermath of Owen’s disappearance in the book version of The Last Thing He Told Me, Hannah is visited by a man claiming to be U.S. Marshall Grady Bradford. He tells her to get a lawyer as she is not Bailey’s legal guardian, and he also tells her not to trust anyone. Maybe not even him. Augusto Aguilera (Made for Love, Too Old to Die Young) is listed as playing Grady, and while no further information has been shared about his role beyond his name, it seems likely that he’ll be playing the man who says he’s a U.S. Marshall.

When Hannah needs to seek out some legal advice, she turns to one person she knows she can trust. Her ex-boyfriend Jake, played by Geoff Stults (Little Fires Everywhere, Wedding Crashers). Jake is a lawyer in New York City, and his first instinct when talking to Hannah in a trailer for The Last Thing He Told Me is to tell her that Owen was probably guilty of a white-collar crime. But when Hannah starts to uncover more evidence that her husband was involved in something darker, Jake tries to help her. He’s really going above and beyond, ex-boyfriend-wise.

It’s important to remember that, amidst all of this life-or-death drama and mystery, poor young Bailey was just trying to live a regular teenage life in the early scenes from The Last Thing He Told Me. And her boyfriend Bobby, played by John Harlan Kim (The Little Things, The Librarians) is part of that life. In fact, Bobby was one of the first people to sort of find out that Owen might not be who he claimed to be. In the book, Bobby goes looking for Owen’s photo in the Princeton alumni roster but can’t find it. Bailey doesn’t twig to the inconsistency at the time... but eventually she starts to wonder.