On the run from the police, S.S. Kumar, a thief, comes across a private invitation to the island of Sir John Locksley addressed to Raja Bahadur Singh. When the Raja is shot, Kumar takes him to a nearby hospital, dons a Sikh’s turban, poses as the Raja’s son and goes to the private island of John. Also attending are K.P.W. Iyengar, Dr. Bukhari, Colonel Columbus, and Countess Rasmussen. A stunned Kumar finds out that all of these invitees are master criminals and gangsters. Kumar’s guise does not fool anyone, including his former sweetheart, Sheila Enders, nevertheless John permits him to stay on, as he feels that Kumar’s career, though an amateur, is consistent with those already present. The reason why John has invited them is to find a successor to take his place as he is dying of cancer. He feels that one of his invitees can be trusted to take his place and for this he has arranged for them to steal a diamond (Shalimar) worth 135 crores of rupees. This gem is placed in a secure place within his palace, which is alarmed, and guarded by armed men 24 hours a day. He challenges one of them to steal the shalimar - but if anyone fails then they are killed instantly. Pitted against such veterans, it looks like Kumar has got himself into a bind that he may not come out of in one piece.