Yep, we've got the words in that sentence in the right place and right order. Beatles man Sir Paul is working on a soundtrack, presumably for the Activision-published 'Destiny'.
The famed musician this afternoon tweeted "I'm really excited to be working on writing music with @bungie, the studio that made Halo."
Accompanying the tweet was the below image, a shot of McCartney with respected Bungie music boss Marty O'Donnell.
It's presumed the music will be for the franchise codenamed 'Destiny', which Bungie exclusive signed to Activision under a widely-scrutinised ten-year publishing deal.
The studio responsible for Xbox flagship series Halo signed with Call of Duty publisher Activision after severing ties with former owner Microsoft and finishing up work on its last Halo game.
The Xbox series is still being made - the fourth game, Halo 4, is due this November. But Bungie has dedicated its time to the new IP project.
McCartney's tweet today follows on from a comment he made in January revealing he was working on a game.
"It's a fascinating market,” the popular lyricist stated.
A new computer game sells so much better than a new CD these days. Young people will hear my music for the first time in a game."
It's not the first time Sir Paul has dabbled in gaming, obviously: he and fellow Beatles star Ringo Starr took to the E3 2009 stage to unveil Harmonix's The Beatles: Rock Band.
Here's the full tweet: