After 17 years, the CBI series of films makes a comeback for its fifth, and supposedly the last, installment with CBI 5: The Brain. Directed by K Madhu (the director of the film series), the movie brings back some of our favourite characters to screen. Like all CBI films, Mammootty stars as the leading role of Sethurama Iyer. In supporting roles, we have Renji Panicker, Ramesh Pisharody, Soubin Shahir, Mukesh, Saikumar, Kottayam Rameshan, and Anoop Menon.

Unlike the teaser cut, CBI 5:The Brain does not probe into the deaths of the Gandhi family members, as was obvious from the trailer as well. The film instead opens into a training class, where two CBI officers, Balagopal and Kishore, recount a particularly challenging case, which confounded the esteemed CBI officers, called the 'Basket Killing'. How the team led by Sethurama Iyer deals with a series of murders forms the crux of the film.

CBI 5: The Brain brings with it nostalgia through several of the original characters, the iconic Iyer-walking BGM, and references to previous movies in the series. However, the way the story unfolds in the fifth installment is a far cry from its predecessors, unlike what many fans worried about. With a runtime of 2 hours and 43 minutes, the movie takes its time to build the story and tension, leaving fans in anticipation of the second half and climax.

Much of the credit of the film's effectiveness goes to SN Swamy's screenplay and Jake's Bejoy's music. Swamy, who wrote all previous CBI films, creates a screenplay void of elements that affect the storytelling. Similarly, Bejoy knew just how much score to add to key scenes to enhance these scenes.

Credit must also be given to cinematographer, Akhil George, who kept the audience on their toes with his stylish shots: One particular chase sequence in the second half stands out for its brilliant use of space and the way it was framed. However, none of these had the same impact as the cast itself.

Seeing Mammootty reprise the role of Sethurama Iyer after over a decade and half is a delight in itself. He looks just as convincing as an esteemed CBI officer as he did in 1988, when the first movie in the series was released. Saikumar as Satyadas was also a marvel to watch, seeing him have a subtle character arc was a bonus indeed. Mukesh returning as Chacko and the throwback to his first appearance in the film series was equally nostalgic.

New members in the team like Renji Panicker and Ramesh Pisharody, among others, convincingly played their respective roles. But the cake was taken by the person, whom most of the audience awaited to return to the movies: Jagathy Sreekumar as Vikram, with his cameo.

CBI 5: The Brain, as mentioned earlier, has a detailed screenplay that takes time to set things up. While that created anticipation, it also caused certain drags in the movie, especially in the second half. A hallmark of CBI films is its detailed and convincing investigation process, which is present in CBI 5, but not without plot holes. Some of the conclusions of the investigation and characters felt abrupt, out-of-character, and rushed. Moreover, in its quest to confuse the viewers, the film becomes slightly convoluted, with its climax leaving a few plotlines with an unsatisfactory end. These, however, will not affect the overall viewing experience, rife with nostalgia and anticipation.