Cognition: An Erica Reed Thriller concludes September 19 on PC and Mac

Adventure game Cognition: An Erica Reed Thriller comes to an end on September 19 with episode four, The Cain Killer. It's due for PC and Mac.

We've followed Phoenix Online Studios' episodic series since the beginning — it started last year in October — and the previous installment, The Oracle, was the best yet.

Cognition stars Erica Reed, an FBI agent investigating a series of weird and gruesome murders that all tie back to her brother's death. By now, she's determined to put a stop to them before she loses anyone else close to her.

Phoenix Online has been slowly converting the games to iPad. So far, the first and second episodes are up on the App Store for $4 each. PC and Mac episodes are reasonably priced, too, at $10 a pop. Season passes are available.

Episode 4: The Cain Killer will launch on Steam, GOG, and Phoenix Online's website. Steam and GOG releases are a first for Cognition (thanks in part to a 10-month Steam Greenlight effort), and the rest of the series will debut on both services alongside episode four.