Season four begins with high rated episode ‘Can You Hear Me Now?’ in this episode CSI team finds human blood on Statue of liberty which leads to murder plan of a musician. Mac plays Bass guitar with a band and his music talent is unveiled. Peyton breaks up with Mac. Mac receives anonymous phone calls at exactly 3:33 from the number 333. Stella dates a man from Antique store. Somebody leaves a puzzle box in Stella’s car which connects to Mac’s past. He goes to Chicago to solve the mystery. A dead body is discovered in Stella’s apartment. The 333 caller questions Mac’s bravery with reference of a case from past. Danny gets involved in a murder case emotionally when he discovers that the victim is a young boy from his neighborhood. The team finds a scientist with extraordinary abilities in mathematics and who can predict the future crimes accurately. The season ends with the episode Hostage.
| No. | Episode | Air date | ||
| 1 | Can You Hear Me Now? | 9/26/2007 | ||
| 2 | The Deep | 10/3/2007 | ||
| 3 | You Only Die Once | 10/10/2007 | ||
| 4 | Time’s Up | 10/17/2007 | ||
| 5 | Down the Rabbit Hole | 10/24/2007 | ||
| 6 | Boo | 10/31/2007 | ||
| 7 | Commuted Sentences | 11/7/2007 | ||
| 8 | Buzzkill | 11/14/2007 | ||
| 9 | One Wedding and a Funeral | 11/21/2007 | ||
| 10 | The Thing About Heroes | 11/28/2007 | ||
| 11 | Child’s Play | 12/12/2007 | ||
| 12 | Happily Never After | 1/9/2008 | ||
| 13 | All in the Family | 1/23/2008 | ||
| 14 | Playing with Matches | 2/6/2008 | ||
| 15 | DOA for a Day | 4/2/2008 | ||
| 16 | Right Next Door | 4/9/2008 | ||
| 17 | Like Water for Murder | 4/16/2008 | ||
| 18 | Admissions | 4/30/2008 | ||
| 19 | Personal Foul | 5/7/2008 | ||
| 20 | Taxi | 5/14/2008 | ||
| 21 | Hostage | 5/21/2008 |
