... that Quincy started out as part of the NBC Sunday Mystery Movie in 1976, and here we are in the final season with an episode that has no mystery to it. The audience sees what happened, and Quincy spends the episode trying to figure it out.
The shop foreman in a furniture business, working alone in the building on a weekend, has an accident with a container of gasoline and lights himself and the business on fire, with him dying and the business burning to the ground in the process. A crusading federal attorney appears, pushing local prosecutors aside, and is just positive that it was arson done by the owner of the store, Ted Locke, with his motive being to collect the insurance and get out from under his lease. With the death of the foreman this becomes murder.
Why does he think this? Because Ted Locke is actually the son of an east coast godfather who has changed his name and fled the east to get away from the family business. But the prosecutor thinks that this move was just to bring mafia business to the west coast. Ted being a friend of Quincy's makes this personal for the medical examiner.
Quincy was trying to make several valid points about the federal grand jury system in this episode, but it just devolves into shrill production. By the end the prosecutor is doing his best George W. Bush imitation - "If you're not with me, you're against me". And the actor portraying the mobster's son is getting over the top melodramatic to the point that I expect him to blurt out - "I'm just a simple fisherman with many friends". See the second Dr. Dolittle film that starred Eddie Murphy for reference.