Camden is first mentioned in Chapter 16 of The Hallmarked Man as being where Niall Semple, missing person and suspect for William Wright, was last seen.

Niall was caught on CCTV at a cash machine on the fourth of June, it “showed a scruffy man with an unkempt beard who, rather incongruously, was holding a metal briefcase. Strike squinted at the hand gripping the briefcase. Either Semple was wearing a heavy metal watch, or he’d handcuffed it to himself.”
There are a few chashpoints in Camden, but we aren’t told which one it was specifically that Niall was last seen at.

In Chapter 59, Jade Semple, wife of the missing Niall, tells Strike that she overheard her husband talking to a woman on the phone and telling her to meet him at the Engineer, which is a pub in Camden. Jade tells Strike that Niall had no connection to Camden that she knew of.
In Chapter 115, Strike drives to Camden and parks on Gloucester Avenue, where the Engineer is located. He enters the pub and asks about Rena Liddell and is told she’d mentioned something about a bridge before she left the pub.
Camden also features in the fourth Strike book, Lethal White. Check that page out below:

