Crito
The dialogue takes place in Socrates' prison cell, where he awaits execution. He is visited before dawn by his old friend Crito, who has made arrangements to smuggle Socrates out of prison to the safety of exile. Socrates seems quite willing to await his imminent execution, and so Crito presents as many arguments as he can in order to persuade Socrates to escape. On a practical level, Socrates' death will reflect badly on his friends--people will think they did nothing to try to save him. Also, Socrates should not worry about the risk or the financial cost to his friends; these they are willing to pay, and they have also arranged to find Socrates a pleasant life in exile. On a more ethical level, Crito presents two more pressing arguments: first, if he stayed, he would be aiding his enemies in wronging him unjustly, and would thus be acting unjustly himself; and second, that he would be abandoning his sons and leaving them without a father.
Phaedo
Simmias confesses that he does not wish to disturb Socrates during his final hours by unsettling his belief in the immortality of the soul, and those present are reluctant to voice their skepticism. Socrates grows aware of their doubt and assures his interlocutors that he does indeed believe in the soul's immortality, regardless of whether or not he has succeeded in showing it as yet. For this reason, he is not upset facing death and assures them that they ought to express their concerns regarding the arguments. Simmias then presents his case that the soul resembles the harmony of the lyre. It may be, then, that as the soul resembles the harmony in its being invisible and divine, once the lyre has been destroyed, the harmony too vanishes, therefore when the body dies, the soul too vanishes. Once the harmony is dissipated, we may infer that so too will the soul dissipate once the body has been broken, through death.