There is more than one artist with this name:
1) Lockdown, from Newcastle in the north east of England play melodic hardcore for fans of Betrayed, Comeback Kid, Ambitions, Sinking Ships etc.
You can either listen to their songs by scrolling down this page, or click here.
Their music is also available for download through iTunes and Napster.
2) Lockdown from New York play a hard brand of NYHC.