The newest member of the CSI team, Jo Danville, a former FBI agent, is welcomed to her new job by stumbling upon the body of a young woman murdered somewhere in the building that houses the NYPD Crime Lab.
When a young woman appears to be strangled while participating in a live online chat that Adam witnesses, the CSIs must determine if it was real or a hoax, and locate where the possible victim is.
When a married couple is found beaten in their home, a mother identifies her son as the killer and the CSIs believe they have their suspect, but all is not what it seems when another witness comes forward.
When the leader of a powerful New York gang, El Puño, is found murdered, the CSIs must find the killer before a street war with a rival gang breaks out. Mac asks the co-founder of El Puño, Luther Devarro, a man he put behind bars years before, for help.
A jewel heist at the penthouse of one of New York's most powerful attorneys takes a bizarre turn and the case leads the CSIs to a seemingly unrelated man in the morgue.
When a badly decomposed body found is an abandoned car on a rooftop, Mac and his team must go up against a killer who is using the parents of his victims to manipulate crime scenes.
Mac is on the hunt for a sniper who is using nitroglycerin in his bullets to explode on impact, and the prime suspect was once a missing boy from one of Mac's old cases.
As the CSIs investigate a case involving a woman who appears to have been scared to death in a supposedly haunted section of Central Park, Mac stumbles on another dead body buried nearby in the same part of the park.
When a woman's body washes up at the South Street Seaport, the CSIs unravel a dark secret from Deputy Chief Carver's past that threatens to shatter his stellar reputation and close-knit family.
Mac and the team search for the killer of a department store manager who was found dead in a holiday display window.
When a man in full clown costume shoots a bakery owner, the CSIs investigate and discover a decision from Flack's past that may put him in jeopardy.
When a Spanish club promoter is found dead, Mac must battle with the head of Barcelona's crime lab to solve the case.
When a tractor-trailer carrying exclusive party guests mysteriously ends up at the bottom of the Hudson River, the CSIs must solve the mystery from the soggy remains.
When the CSIs track down a suave and charming hitman, their investigation uncovers a conspiracy with far-reaching implications.
When a serial rapist is found murdered, restrained in the same manner as his victims, the CSIs weigh a feeling of justice against their sense of duty to pursue the killer.
When a conspiracy-obsessed woman is found dead, the CSIs investigate and discover that some of her theories may have had some truth to them.
When a popular student and star pupil at Manhattan's most elite private school is murdered, the CSIs find themselves immersed in the highly competitive world of over-privileged youth.
Jo balances personal and professional challenges when her adopted daughter, Ellie, is the key witness in a murder investigation.
While the team investigates the explosion of a gourmet food truck, Sheldon's new relationship could get him in big trouble at the lab.
The CSIs investigate a woman's death as the work of a serial killer, and Mac reconnects with his first partner after an ex-con they put away begins stalking him.
After a hail of gunfire tears through the crime lab, Mac and his ex-partner become part of a vendetta 17 years in the making.
Following a near-death experience, Mac becomes determined to close his last remaining unsolved case.
