The Good Guys Season 1 Episode 5 (06/28/10)
After admitting under oath that his investigative methods weren't legal, Dan is responsible for a drug smuggler going free. As a result, the department pulls all resources from the case and Dan vows to bring the man to justice using only the money in his pocket: $3.52.
This largely required the assistance of Julian, who gave Dan information with the promise that his five-year jail sentence would be reduce.
Soon enough, Jack realized that it was his job as a partner to help Dan with the mission and the pair set out to do what they do best: bust some punks!
They were eventually successful, of course, with Julian coming to the rescue when a bad guy had a gun on the tandem; and also with Liz finally getting to do something except look pretty for Jack. That was the most important step this episode took.
We also got to witness some truly handy police work from Dan, who uncovered some evidence due to slight of hand and proved that he's more than just a washed up detective with an awesome mustache.