Lion & Lamb is a mystery thriller co-authored by bestselling novelist James Patterson and Marvel comics writer Duane Swierczynski, published by Little, Brown and Company (an imprint of Hachette Book Group) in August 2023. The hardcover edition runs 400 pages with an ISBN of 978-0-316-40489-1.

Philadelphia is rocked when Eagles starting quarterback Archie Hughes is found shot dead in his Maserati on a freezing January night, his Super Bowl ring and watch missing. The prime suspect is his wife, Grammy-winning singer and film star Francine Pearl Hughes. Rival private investigators Veena Lion and Cooper Lamb are each hired to work opposite sides of the case: Veena assists the district attorney in building a case against Francine, while Cooper works on her defense. As their investigations deepen, questions about Archie's own innocence muddy the waters, and an unexpected partnership—and romance—develops between the two detectives.

Featuring a sharp ensemble cast including Cooper's two preternaturally clever kids and his Rhodesian ridgeback puppy, Lion & Lamb delivers a fast-paced, character-driven mystery set against the backdrop of Philadelphia's sports and celebrity culture. The novel earned a 3.96 average rating from over 14,000 Goodreads readers and received a starred review from Publishers Weekly, which called it "a fun ride."