top 10 single in the US, and became his first number one on the Adult Pop Songs and Adult Contemporary charts. The song later reached number one in the UK. Also in 2015, Mendes opened for Taylor Swift during 1989 World Tour dates for North America and recorded "Believe" for the soundtrack of Disney Channel Original Movie Descendants. In late 2015, Mendes and Camila Cabello, who was at the time a member of the group Fifth Harmony, released their collaborative single "I Know What You Did Last Summer". The song was included on Mendes' Handwritten Revisited reissue. Mendes was listed among Times "25 Most Influential Teens of 2014", debuting in the list after being the youngest-ever artist to debut in the top 25 of Billboard Hot 100. He was listed in Times "The 30 Most Influential Teens of 2015", making the list after his debut album topped the Billboard 200 and his single "Stitches" made the top 10 in the US and other countries. 2016–2017: Illuminate On January 21, 2016, Mendes made his acting debut on The CW's The 100 third-season premiere. He later announced his second world tour as a headliner, the Shawn Mendes World Tour, which started in March 2016 and sold out 38 shows in North America and Europe within minutes. Mendes released "Treat You Better", the lead single from his second studio album, in June 2016. In the US, the single reached the top 10 on the Billboard Hot 100, became his second single to peak atop both the Adult Contemporary and Adult Pop Songs chart, and was certified triple platinum. It also went top 10 in the UK. The album, Illuminate, was released on September 23, 2016, and debuted at number one on the US Billboard 200 with 145,000 equivalent album units, including 121,000 in pure album sales and was certified platinum. It debuted atop the charts in Canada, becoming his second number one album in his home country. "Mercy" was released as the second single on August 18, 2016, which entered the top 20 in the US and the UK and was certified double platinum. Mendes released the live album Live at Madison Square Garden in December 2016. He appeared as the musical guest on Saturday Night Live, December 3, 2016. In April 2017, Mendes embarked on his Illuminate World Tour, which sold-out arenas around the world such as Los Angeles' Staples Center and