After a high school party ends in the death of a popular girl who was suffocated with a menstrual cup, amateur sleuths Kelly and Annie must stop a menstrual murderer when a second student turns up dead with a sanitary pad across the eyes.

There’s never a good time to find a dead body, sure. But what about finding a dead body while you’re trying to kiss your crush? Kerry had different plans for her first high school party—like not going. All she wanted to do was stay home in the safety of retro rom-coms and her strict retainer schedule. Instead her BFF, fiercely outgoing mystery-fanatic Annie, has roped her into going to the party to investigate who’s cyberbullying Heather, the most popular girl in school. Finding herself getting close with her dreamy crush is odd enough, but when the two of them discover Heather’s second in command, Selena, suffocated with a menstrual cup, things get really weird. And when a second student turns up dead, this time with a sanitary pad across the eyes, Annie and Kerry—no matter how much she resists—are officially on the case to stop the menstrual murderer . . . period.