In 4.10 "The Thing About Heroes...", Mac continues his Chicago investigation and follows the clues to a body hanging in an unused floor of the Chicago Tribune building. A hangman puzzle written on the wall leaves out the letters that spell "Coward". The decomposed body is revealed to be that of Bobby Toole who died thirty years ago. Mac goes and talks to a former friend of his named Jimmy. He asks Jimmy if he's the stalker and if it's because of his brother Will's death. Mac has proof the bloody T-shirt is Will's and says they were the only ones who knew that Bobby Toole killed Will and that they killed Bobby. Jimmy is incensed at the idea and that Mac is acting high and mighty after he apparently let Will down that night. Jimmy says Mac has no idea what it was like seeing his father cry and lying to his younger brother Andy about Will's death. Then Jimmy storms away. Mac turns around to see Flack standing there. Since an attempt was made on the team's life while Mac was away, and the chief had been getting angry calls about Mac's work from Chicago police, Don has been sent to help Mac clean things up quickly. Mac tells Flack when he and Jimmy were both 14 they used to tag along with Jimmy's brother Will (age 16) to make deliveries for a guy named Sal Marchetti. One night, they delivered money to Bobby Toole, but Toole got upset that it wasn't all there. He began to beat Will. Jimmy grabbed Bobby's gun but was hit and dropped it. Jimmy yelled for Mac to get the gun and he did but Mac couldn't bring himself to pull the trigger. Jimmy grabbed the gun from Mac and shot and killed Toole. They took Will to the ER where he died and told the police they were mugged, but they didn't see by who. They then told Sal what happened and Sal told them he would help hide the evidence.
By the end of the fourth season, Mac is tricked and taken hostage by a criminal named "Joe". At the beginning of Season 5, he lost consciousness and after waking forgot what were the last things he did. He later revives his memories and is back on the case to find Joe. At the end of 5.01 "Veritas", he finally arrests Joe and tells him that he made him get very "pissed off".
Year: 2011. Five years passed since the Second Disaster, which eclipsed the events of April 1986. The Zone is shaken by frequent and powerful blowouts, which move anomaly fields, opening new routes to previously inaccessible locations. Stalker factions fight for the new territories and key points. A lot of stalkers die, but newbies keep on arriving.The action takes place one year prior to the events of S.T.A.L.K.E.R.: Shadow of Chernobyl, one year before Strelok's most successful trip to the center of the Zone - the third one. We will learn about Strelok and his squad from another character's vantage point. The Zone is waiting for you ahead, new locations and unknown threats, spatial holes and monsters hiding in the fog, pitch-black nights and saving rays of a rising sun. Try to avoid anomalies and hide from blowouts, discover the Zone and collect artifacts, cure radioactive irradiation and fight for any stalker faction you like! Only then will you uncover the truth about Strelok and how he happened to get inside the death track and receive the S.T.A.L.K.E.R. tattoo on his arm. 2b1af7f3a8