Roland's Journal is a book found in The Knife of Dunwall.
So, Timsh thinks he's invincible because he carries a letter from the Lord Regent giving him legal immunity from the state seizing his goods in case of plague. He carries it everywhere, like a talisman. But he's also drafted the instrument of his own destruction. The document he uses for evictions is a generic form drafted by the office of the Lord Regent. It was trivial to acquire a blank one. Acquiring a forgery of the Lord Regent's signature was less easy, but thankfully some of my old connections are still loyal. Now, all I need to do is swap the two documents. Getting close enough to Timsh to do it won't be easy... I may need help from a professional.
Once that's done, the fool just needs a push to go down, and that's the second part.
Inside Timsh's basement there's a device that circulates air in the building. If some - material - happened to find its way into the device, the building would reek like a weeper's den. I had to be particular about the actual material, as I do not wish to infect the guard(s) or servants with plague and cause needless suffering. The unsavory gentlewoman living in Unit 10 has offered to provide the odorous item, and a study [sic] sack to contain it. She craves my rune in exchange, so I will be forced to part with it. She has given me a key to her unit so I can go and get the sack when I am ready to make my move.
It can be found on a mattress in the Legal District in Apartment 7.