Plummer was heavily recruited out of high school, getting her first scholarship offer in the 7th grade.[5] She ultimately selected Stanford on a full athletic scholarship.[6] While at Stanford, she helped Stanford win NCAA national championships in 2016, 2018 and 2019. She was named to the NCAA all-tournament team all three years, and won the Most Outstanding Player award in 2018 and 2019. As a freshman, she won National Freshman of the Year by the AVCA, and in 2017 and 2018 she was named the National Player of the Year.[1]
On December 30, 2019, Plummer signed her first professional contract with Italian side Saugella Team Monza.[7] She made her Serie A debut on January 19 in Monza's 3-2 defeat against Zanetti Bergamo in which she came on as a substitute and scored 9 points.[8] She was the top scorer in Monza's Coppa Italia quarter final upset over Igor Gorgonzola Novara and played a key role for her team to reach their second-ever Coppa Italia final four,[9] where they were eventually defeated by Unet E-Work Busto Arsizio in the semi-finals.[10] In CEV Cup, Plummer only played in Monza's 3-1 loss in the second leg of the round of 16 match-up against Dinamo Kazan which eliminated them from the competition.[11][12]
On 10 May 2024, Turkish club Eczacıbaşı Dynavit announced the addition of Plummer to their roster.[15]
USA National Team
In May 2021, Plummer was named to the 18-player roster for the FIVB Volleyball Nations League tournament.[16] that was played May 25-June 24 in Rimini, Italy. She led the team with 14 kills and two blocks in her debut, when they swept Dominican Republic in team USA's opening match.[17]