This is a 3-part study. Parts 1 and 2 are randomized, double-blind, placebo-controlled investigations of single ascending doses (SAD) (Part 1) and multiple ascending doses (MAD) (Part 2) of orally administered BLU-808 in healthy adult participants. Part 2 will also include an evaluation of the effect of multiple doses of BLU-808 on the single-dose pharmacokinetics (PK) of midazolam. Part 3 is an open-label, 2-sequence, 2-period, food effect (FE) study in healthy adult participants.