[Daniel Seltzer as Cohn in "Knock Knock".]
["Knock Knock" theater still.]
[Jules Feiffer and the cast of "Knock Knock".]
[Neil Flanagan as Abe in "Knock Knock".]
[Judd Hirsch in "Knock Knock".]
[Leonard Frey in "Knock Knock".]
[Daniel Seltzer as Cohn and Nancy Snyder as Joan in "Knock Knock".]
[Daniel Seltzer as Cohn and Neil Flanagan as Abe in "Knock Knock".]
[John Heffernan as Abe in "Knock Knock".]