On their second album, post-punkers Bloc Party attempt to portray 48 hours in the life of their native London. Over 51 minutes of techno-tweaked rock, yelpy, tortured singer Kele Okereke takes on a mix of dreary characters, from powder-snorting hedonists (''On'') to bored blue-collar stiffs (''Waiting for the 7:18''). Too often, the music on A Weekend in the City is less memorable than the ambitious subject matter. Still, drummer Matt Tong pumps out herculean disco-rock beats that'll work any nightclub into a froth.

