There were just five minutes of normal time remaining when Hanson levelled to hand third-bottom Bradford a share of the points to keep them three points off bottom spot, which is now occupied by Dagenham & Redbridge.
Bradford dominated the first half but the nearest they came to scoring was a minute before the break when skipper Michael Flynn saw his shot cleared off the line by defender Darren Purse with keeper Jake Cole beaten.
Plymouth went in front in the 59th minute from their first corner of the game. The home defence failed to clear Will Atkinson’s flag-kick and skipper Simon Walton’s 15-yard shot was deflected into the net by Craig Sutherland.
The Bantams pressed hard for an equaliser and their pressure paid off in the 85th minute when Kyel Reid delivered a low cross from the left and Hanson scored with a superbly-taken left-footed shot just inside the near post.
Flynn and Ricky Ravenhill missed good chances to win the game for the home side in the closing stages as Plymouth were reduced to 10 men when Onismor Bhasera was sent off for a second bookable offence.