six o'clock
`` I know all this is dangerous , '' said Mr. Everett , `` but you boys are now working for your country , and as you have taken the responsibility you must be prepared to carry it out to the end . For safety 's sake , however , I am going to propose the following measure . Come back to the house as soon as you have either succeeded or failed in your mission . If you are not here by six o'clock , I will take it on myself to summon help from the Customs authorities up the line , or arm a posse here and search Green 's house . I hope that wo n't be necessary , for it would put an end to discovering what is in the wind , but that is better than that you boys should fall into trouble . Now God speed you on your way . '' They said goodbye to Mr. Everett , after shaking hands with him , and once again hearing his wishes for good luck .