An Obol for Charon

Pike sets out after Spock's shuttle, using information brought by his Enterprise first officer, Number One, but a vast, ancient sphere pulls Discovery out of warp. Systems fail one after another, and the universal translator scrambles every language aboard, leaving Saru, who speaks more than ninety, to help untangle it. Then Saru falls gravely ill. His threat ganglia are changing, the sign that Kelpiens are taught means madness and death, and he prepares to die with Burnham at his side. Meanwhile Tilly, still host to the spore organism, is overwhelmed by it, and Stamets and Reno race to save her. The sphere proves to be dying rather than hostile, and before it perishes it passes its vast store of knowledge into Discovery's computer. Saru's ganglia fall away and he survives, free at last of the fear that has ruled his life. But the organism cocoons Tilly and vanishes with her.