Twenty One is the second studio album by Mystery Jets, released in the UK on 24 March 2008.

[13] The first single from the album, "Young Love" featuring Laura Marling, was released on 10 March 2008.

The album originally reached #50 in the UK Albums Chart but was hastily rereleased with an additional cover of Aztec Camera's hit single "Somewhere in My Heart" to coincide with the release of eighties-themed single "Two Doors Down" (featuring sax by Nik Carter),[14] which peaked at #24 in the UK Singles Chart.

All three songs, in addition to "Flakes" (which was released as a free download of the week via the UK iTunes Store) had music videos shot for them.

The 7" vinyl EP of "Half in Love with Elizabeth" features the band performing "Flakes" with Florence Welch of Florence + the Machine performing vocals, this one of her earliest releases, following the release of her first single "Kiss with a Fist" by only a few months.