Reviewing Kennedy's Brain in The Independent, Paul Binding found that Henrik Cantor, "an idealistic young Swede" whose death, and its subsequent investigation by his mother Louise provides the narrative drive of the book, "has acknowledged that there exist those who, deliberately and using all their intelligence and money, seek to profit from the distress of others.

In contrast, Louise herself, her father, Artur, up north in Mankell's beloved forests of Härjedalen, and her hopeless but touching husband, Aron, are living beings about whom we can imaginatively care.

Preston added, "It would be giving too much away to reveal more, but suffice it to say that Kennedy's Brain bears certain thematic resemblances to John le Carré's The Constant Gardener.

The main difficulty is that the indignation with which it is suffused – a note in the epilogue refers to how anger was Mankell's driving force when he was writing it – seems to have played havoc with his normally sure-footed exposition".

He found the plot to be, "a succession of coincidences and fortuitous revelations which never gels, or develops any tension", before concluding that, "As usual with Mankell there are some great lines – 'Sorrow is like mice, it always finds a way in,' he notes at one point.